diff --git a/movement_faces.h b/movement_faces.h
index fc43716d..81ca394f 100644
--- a/movement_faces.h
+++ b/movement_faces.h
@@ -73,4 +73,5 @@
 #include "wareki_face.h"
 #include "deadline_face.h"
 #include "wordle_face.h"
+#include "tide_face.h"
 // New includes go above this line.
diff --git a/watch-faces.mk b/watch-faces.mk
index 22e262cf..6c8000d7 100644
--- a/watch-faces.mk
+++ b/watch-faces.mk
@@ -48,4 +48,5 @@ SRCS += \
   ./watch-faces/sensor/lis2dw_monitor_face.c \
   ./watch-faces/complication/wareki_face.c \
   ./watch-faces/complication/deadline_face.c \
+  ./watch-faces/complication/tide_face.c \
 # New watch faces go above this line.
diff --git a/watch-faces/complication/tide_face.c b/watch-faces/complication/tide_face.c
new file mode 100644
index 00000000..e3cd9577
--- /dev/null
+++ b/watch-faces/complication/tide_face.c
@@ -0,0 +1,402 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2025 Mathias Kende
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <math.h>
+#include <stdlib.h>
+#include <string.h>
+#include "tide_face.h"
+#include "watch.h"
+#include "watch_common_display.h"
+#include "watch_utility.h"
+
+// Parameters taken from the moon_phase_face.c file.
+#define LUNAR_DAYS 29.53058770576
+#define FIRST_MOON 947182440 // Saturday, 6 January 2000 18:14:00 in unix epoch time
+#define SEMI_DIURNAL_TIDAL_PERIOD (LUNAR_DAYS / (LUNAR_DAYS - 1) * 12 * 3600) // 12h25m in seconds
+
+#ifndef M_PI
+#define M_PI 3.14159265358979
+#endif
+
+typedef enum {
+    spring_tide,  // Less than 1.8 days away from a full or new moon.
+    neap_tide,  // Less than 1.8 days away from a first or third quarter moon.
+    medium_tide,  // The rest
+} tide_amplitude_t;
+
+static tide_amplitude_t _get_tide_amplitude(uint32_t time) {
+    // Moon age in days, looped over beetween new and full moon (so age is 14.7 days at most).
+    double moon_age = fmod(((double)(time - FIRST_MOON)) / 86400, LUNAR_DAYS / 2);
+
+    if (moon_age <= LUNAR_DAYS / 16 || moon_age >= LUNAR_DAYS * 7 / 16) {
+        return spring_tide;
+    } else if (moon_age > LUNAR_DAYS * 3 / 16 && moon_age < LUNAR_DAYS * 5 / 16) {
+        return neap_tide;
+    } else {
+        return medium_tide;
+    }
+}
+
+typedef enum {
+    empty,        // No tide data set.
+    current,      // Default screen, showing the current tide.
+    future,       // Screen showing the time of future high and low tides.
+    setting_hour, // Setting screen, setting the hour of the next high tide.
+    setting_min,  // Setting screen, setting the minute of the next high tide.
+} tide_mode_t;
+
+typedef enum {
+    high_tide,
+    low_tide,
+} tide_type_t;
+
+typedef struct {
+    tide_mode_t mode;
+    bool start_setting;  // we entered the setting mode but did not yet changed any value.
+    uint32_t next_high_tide;
+    uint32_t last_current_update_time;
+    uint32_t future_tide_time;
+    tide_type_t future_tide_type;
+} tide_state_t;
+
+void tide_face_setup(uint8_t watch_face_index, void** state_ptr) {
+    if (*state_ptr == NULL) {
+        // Boot time initialization.
+        *state_ptr = malloc(sizeof(tide_state_t));
+        tide_state_t* state = (tide_state_t*)*state_ptr;
+        state->mode = empty;
+    }
+}
+
+uint32_t _get_current_unix_time() {
+    return watch_utility_date_time_to_unix_time(movement_get_utc_date_time(), 0);
+}
+
+void _move_next_high_tide(tide_state_t* state, uint32_t now) {
+    while (state->next_high_tide > now + SEMI_DIURNAL_TIDAL_PERIOD) {
+        state->next_high_tide -= SEMI_DIURNAL_TIDAL_PERIOD;
+    }
+    while (state->next_high_tide < now) {
+        state->next_high_tide += SEMI_DIURNAL_TIDAL_PERIOD;
+    }
+}
+
+void tide_face_activate(void* context) {
+    tide_state_t* state = (tide_state_t*)context;
+    if (state->mode != empty) {
+      state->mode = current;
+    }
+    // int64 so that the substraction below works (we need a signed number and int32 will overflow soon).
+    // using int64 everywhere for the unix time would probably be better.
+    int64_t now = _get_current_unix_time();
+    if (llabs(now - state->next_high_tide) > 60 * 86400) {
+        // We revert to the empty mode if the next high tide is more than 2
+        // months from now, to avoid accumulating too much errors.
+        state->mode = empty;
+        return;
+    }
+    _move_next_high_tide(state, now);
+}
+
+static void _set_pixel(segment_mapping_t mapping) {
+    watch_set_pixel(mapping.address.com, mapping.address.seg);
+}
+
+static void _draw_tide_amplitude(uint32_t time) {
+    const digit_mapping_t* digit_mapping =
+        watch_get_lcd_type() == WATCH_LCD_TYPE_CLASSIC ? Classic_LCD_Display_Mapping : Custom_LCD_Display_Mapping;
+    switch (_get_tide_amplitude(time)) {
+        case spring_tide:
+            _set_pixel(digit_mapping[9].segment[0]);  // top horizontal bar on the bottom-right character.
+        case medium_tide:
+            _set_pixel(digit_mapping[9].segment[6]);  // mid horizontal bar on the bottom-right character.
+        case neap_tide:
+            _set_pixel(digit_mapping[9].segment[3]);  // bottom horizontal bar on the bottom-right character.
+            break;
+    }
+}
+
+static void _draw_day_and_time(uint32_t time, bool show_day, bool show_hour, bool show_minute) {
+    watch_date_time_t date_time = 
+        watch_utility_date_time_from_unix_time(time, movement_get_current_timezone_offset());
+    bool pm = false;
+    if (movement_clock_mode_24h() == MOVEMENT_CLOCK_MODE_12H) {
+        pm = watch_utility_convert_to_12_hour(&date_time);
+    } else {
+        watch_set_indicator(WATCH_INDICATOR_24H);
+    }
+    if (pm) {
+        watch_set_indicator(WATCH_INDICATOR_PM);
+    }
+
+    if (show_hour) {
+        char tide_hour[3];
+        sprintf(tide_hour, "%2u", date_time.unit.hour);
+        watch_display_text(WATCH_POSITION_HOURS, tide_hour);
+    }
+    if (show_minute) {
+        char tide_minute[3];
+        sprintf(tide_minute, "%02u", date_time.unit.minute);
+        watch_display_text(WATCH_POSITION_MINUTES, tide_minute);
+    }
+    if (show_day) {
+        char tide_day[3];
+        sprintf(tide_day, "%2u", date_time.unit.day);
+        watch_display_text(WATCH_POSITION_TOP_RIGHT, tide_day);
+    }
+
+    watch_set_colon();
+}
+
+static void _draw(tide_state_t *state, uint32_t now, uint8_t subsecond) {
+    watch_clear_display();
+    switch (state->mode) {
+        case empty:
+            watch_display_text_with_fallback(WATCH_POSITION_TOP, "TIDE", "TI");
+            watch_display_text(WATCH_POSITION_BOTTOM, "----");
+            break;
+        case current: {
+            double tide_age = state->next_high_tide - now;
+            _draw_tide_amplitude(now);
+            double tide_percent = (cos(tide_age / SEMI_DIURNAL_TIDAL_PERIOD * M_PI * 2) + 1) * 50;
+            if (tide_percent < 5) {
+                watch_display_text_with_fallback(WATCH_POSITION_TOP, "LOW", "LO");
+            } else if (tide_percent > 95) {
+                watch_display_text_with_fallback(WATCH_POSITION_TOP, "HIGH", "HI");
+            } else {
+                if (state->next_high_tide - now < SEMI_DIURNAL_TIDAL_PERIOD / 2) {
+                    watch_display_text_with_fallback(WATCH_POSITION_TOP, "FLOOd", "FL");
+                } else {
+                    watch_display_text_with_fallback(WATCH_POSITION_TOP, "EBB", "EB");
+                }
+                if (watch_get_lcd_type() == WATCH_LCD_TYPE_CLASSIC) {
+                    uint8_t tide_upercent = tide_percent;
+                    char hour[2];
+                    char minute[2];
+                    hour[0] = minute[1] = ' ';
+                    hour[1] = '0' + tide_upercent / 10;
+                    minute[0] = '0' + tide_upercent % 10;
+                    // We use the second hour digit for our first digit, as it’s
+                    // more capable than the first hour or minute digits.
+                    watch_display_text(WATCH_POSITION_HOURS, hour);
+                    watch_display_text(WATCH_POSITION_MINUTES, minute);
+                } else {
+                    char tide_text[7];
+                    uint8_t tide_upercent = tide_percent;
+                    sprintf(tide_text, "%2hhu", tide_upercent);
+                    watch_display_text(WATCH_POSITION_HOURS, tide_text);
+                    watch_display_text(WATCH_POSITION_MINUTES, "o#");  // # is rendered as °, o° looks like a percent sign, maybe...
+                }
+            }
+            break;
+        }
+        case future:
+            if (state->future_tide_type == low_tide) {
+                watch_display_text_with_fallback(WATCH_POSITION_TOP_LEFT, "LOW", "LO");
+            } else {
+                watch_display_text_with_fallback(WATCH_POSITION_TOP_LEFT, "HIG", "HI");
+            }
+            _draw_day_and_time(state->future_tide_time, true, true, true);
+            _draw_tide_amplitude(state->future_tide_time);
+            break;
+        case setting_hour:
+        case setting_min:
+            if (state->start_setting) {
+                watch_display_text_with_fallback(WATCH_POSITION_TOP, "HIGH", "HI");
+            } else {
+                watch_display_text_with_fallback(WATCH_POSITION_TOP_LEFT, "HIG", "HI");
+            }
+            _draw_day_and_time(state->next_high_tide, !state->start_setting,
+                               (state->mode != setting_hour || subsecond % 2), (state->mode != setting_min || subsecond % 2));
+            break;
+    }
+}
+
+static void _offset_next_high_tide(tide_state_t* state, int16_t offset) {
+    state->next_high_tide += offset;
+    if (state->next_high_tide % 60) {
+        state->next_high_tide -= state->next_high_tide % 60;
+    }
+    state->start_setting = false;
+}
+
+bool tide_face_loop(movement_event_t event, void* context) {
+    tide_state_t* state = (tide_state_t*)context;
+    uint32_t now = _get_current_unix_time();
+
+    // TODO: handle long press in setting mode.
+    switch (event.event_type) {
+        case EVENT_ACTIVATE:
+            _draw(state, now, event.subsecond);
+            if (state->mode == current) {
+                state->last_current_update_time = now;
+            }
+            break;
+        case EVENT_TICK:
+            switch (state->mode) {
+                case current:
+                    if (now - state->last_current_update_time >= 60) {
+                        _move_next_high_tide(state, now);    
+                        _draw(state, now, event.subsecond);
+                        state->last_current_update_time = now;
+                    }
+                    break;
+                case setting_hour:
+                case setting_min:
+                    _draw(state, now, event.subsecond);
+                    break;
+                default:
+                    break;
+            }
+            break;
+        case EVENT_LOW_ENERGY_UPDATE:
+            _draw(state, now, event.subsecond);
+            if (watch_get_lcd_type() == WATCH_LCD_TYPE_CLASSIC) {
+                watch_start_sleep_animation(500);
+            } else {
+                watch_set_indicator(WATCH_INDICATOR_SLEEP);
+            }
+            break;
+        case EVENT_LIGHT_BUTTON_DOWN:
+            switch (state->mode) {
+                case setting_hour:
+                    state->mode = setting_min;
+                    _draw(state, now, event.subsecond);
+                    break;
+                case setting_min:
+                    state->mode = current;
+                    _move_next_high_tide(state, _get_current_unix_time());
+                    movement_request_tick_frequency(1);
+                    _draw(state, now, event.subsecond);
+                    break;
+                default:
+                    movement_illuminate_led();
+                    break;
+            }
+            break;
+        case EVENT_LIGHT_LONG_PRESS:
+            if (state->mode == future) {
+                state->mode = current;
+                _draw(state, now, event.subsecond);
+                state->last_current_update_time = now;
+            }
+            break;
+        case EVENT_ALARM_BUTTON_DOWN:
+            switch(state->mode) {
+                case setting_hour:
+                    _offset_next_high_tide(state, 3600);
+                    break;
+                case setting_min:
+                    _offset_next_high_tide(state, 60);
+                    break;
+                default:
+                    break;
+            }
+            _draw(state, now, event.subsecond);
+            break;
+        case EVENT_ALARM_BUTTON_UP:
+            // We react to UP event only so that we don’t switch to a future day at the beginning of a long press.
+            switch(state->mode) {
+                case current:
+                    if (state->next_high_tide - now > SEMI_DIURNAL_TIDAL_PERIOD / 2) {
+                        state->future_tide_time = state->next_high_tide - SEMI_DIURNAL_TIDAL_PERIOD / 2;
+                        state->future_tide_type = low_tide;
+                    } else {
+                        state->future_tide_time = state->next_high_tide;
+                        state->future_tide_type = high_tide;
+                    }
+                    state->mode = future;
+                    break;
+                case future:
+                    state->future_tide_time += SEMI_DIURNAL_TIDAL_PERIOD / 2;
+                    state->future_tide_type = state->future_tide_type == low_tide ? high_tide : low_tide;
+                    break;
+                default:
+                    break;
+            }
+            _draw(state, now, event.subsecond);
+            break;
+        case EVENT_ALARM_LONG_PRESS:
+            switch(state->mode) {
+                case empty:
+                  state->next_high_tide = _get_current_unix_time();
+                  // fallthrough intended.
+                case current:
+                case future:
+                    state->mode = setting_hour;
+                    state->start_setting = true;
+                    movement_request_tick_frequency(4);
+                    break;
+                case setting_hour:
+                case setting_min:
+                    break;
+            }
+            _draw(state, now, event.subsecond);
+            break;
+        case EVENT_MODE_BUTTON_DOWN:
+            switch(state->mode) {
+                case setting_hour:
+                    _offset_next_high_tide(state, -3600);
+                    break;
+                case setting_min:
+                    _offset_next_high_tide(state, -60);
+                    break;
+                default:
+                    return movement_default_loop_handler(event);
+            }
+            _draw(state, now, event.subsecond);
+            break;
+        case EVENT_MODE_BUTTON_UP:
+        case EVENT_MODE_LONG_PRESS:
+            switch(state->mode) {
+                case setting_hour:
+                case setting_min:
+                    break;
+                default:
+                    return movement_default_loop_handler(event);
+            }
+            break;
+        case EVENT_TIMEOUT:
+            if (state->mode == setting_min || state->mode == setting_hour) {
+                state->mode = current;
+                _draw(state, now, event.subsecond);
+            }
+            // Passthrough intended:
+            // Delegate the resign behavior to the default loop handler.
+        default:
+            return movement_default_loop_handler(event);
+    }
+
+    return true;
+}
+
+void tide_face_resign(void* context) {
+    // Any cleanup needed before the watch face goes off-screen.
+    tide_state_t* state = (tide_state_t*)context;
+    if (state->mode == setting_hour || state->mode == setting_min) {
+        // Not strictly needed because it will be done upon re-entering the
+        // watch face. But let’s leave a clean state.
+        _move_next_high_tide(state, _get_current_unix_time());
+    }
+}
diff --git a/watch-faces/complication/tide_face.h b/watch-faces/complication/tide_face.h
new file mode 100644
index 00000000..648d99a4
--- /dev/null
+++ b/watch-faces/complication/tide_face.h
@@ -0,0 +1,80 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2025 Mathias Kende
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#pragma once
+
+#include "movement.h"
+
+/*
+ * TIDE COMPUTATION face
+ *
+ * Computes the time of the next high and low tides in your areas as well as
+ * their magnitudes and gives an approximation of the current tide.
+ * 
+ * For now, this face only handle a theoretical perfect semi-diurnal tide,
+ * similarly to what some Casio watches are doing. In the future, it may be
+ * possible to handle more precise computation by sending the harmonics
+ * coeficients of the tides over IR.
+ * 
+ * To configure the face, long press the Alarm button to enter the setting mode
+ * then set the time of the high tide in your area. You can move the hour using
+ * the Alarm and Mode button to go up and down, then press the Light button to
+ * set the minutes in the same way. Notice that if you overflow the minutes then
+ * the hour will change. Similarly, when the hours overflow, the day for the
+ * tide (shown in the upper right corner) is changed too (however there is no
+ * direct way to set the day). You must be sure to select the right day for the
+ * tide that you are currently entering.
+ * Note that, if you set the high tide value for a day with a full or new moon,
+ * the computation will be slightly more precise.
+ * Because the Mode button is used, you must first press the Alarm button once
+ * or twice, to exit the settings, before pressing Mode to exit the watch face.
+ * 
+ * Once configured, the face start by showing the state of the current tide
+ * (low, flowing, high, or ebbing) at the top of the screen. If the tide is
+ * flowing or ebbing, the bottom left part of the screen also shows the current
+ * hight of the tide as a percentage of the total tide. The bottom right portion
+ * of the screen shows a representation of whether the current tide is a neap
+ * or spring tide, or an intermediate one.
+ * 
+ * You can then repeatedly press the Alarm buttom to see the time of the future
+ * high and low tides. The bottow right corner has the same representation of
+ * the amplitude of the tide and the top right corner has the day of the month
+ * for which the tide is shown.
+ * 
+ * You can long press the Light button to come back to the state of the current
+ * tide. Exiting and re-entering the watch face will have the same effect.
+ */
+
+void tide_face_setup(uint8_t watch_face_index, void ** context_ptr);
+void tide_face_activate(void *context);
+bool tide_face_loop(movement_event_t event, void *context);
+void tide_face_resign(void *context);
+
+#define tide_face ((const watch_face_t){ \
+    tide_face_setup, \
+    tide_face_activate, \
+    tide_face_loop, \
+    tide_face_resign, \
+    NULL, \
+})