Marevia - US Tide Charts
Marevia is a tide table for the US coast. Pick one of more than 3,400 tide stations from Maine to Alaska, Hawaii and the territories, and it shows the day's high and low tides with their times and heights, a curve of the whole day, and a large countdown to the next high or low.
It is made for people who plan around the water: anglers picking a window on a falling tide, tide-poolers waiting for a good low, kayakers who would rather not fight the current, and anyone launching from a shallow ramp. You can step through the days or jump to any date up to a year ahead.
The predictions come from the official US tide prediction service (NOAA), and every time is shown in the station's own local time, exactly as published. Your favorites and settings stay in this browser; there is no account to create.
The app runs entirely in your browser. What you enter is saved only on this device.
How to use Marevia
- Find a station. Open the Stations tab. Type a place name or a two-letter state code (for example "Monterey" or "ME"), switch to Map to browse pins around the coast, or use Near me to sort stations by distance. Location is optional; search and the map reach every station without it.
- Read the day at a glance. Tap a station to open it on the Tides tab. The top shows whether the tide is rising or falling and how long until the next high or low, followed by the daily curve and a list of every high and low with its time and height.
- Move to another date. Use the arrows beside the date to step one day at a time, or tap the date to pick any day up to a year ahead. When you are away from today, a calendar button next to the arrows brings you back.
- Save the spots you use. Tap the star on a station. The Favorites tab lists your saved places with the next high or low and how far away it is, so you can compare spots without opening each one. The web version keeps up to three favorites.
- Choose units and time format. In Settings, switch tide height between feet and meters and the clock between 12-hour and 24-hour. The change applies everywhere straight away.
- Check where the numbers come from. Settings > Data details shows the station ID, coordinates, station type, the vertical datum (MLLW) and when the predictions were downloaded. You can also re-download them there, or export your favorites and settings as a JSON file.
Features
- More than 3,400 US tide stations bundled with the app, searchable by name, state or station ID
- Map of stations with OpenStreetMap tiles, plus a nearest-station list from your location
- High and low tide times and heights for any day up to a year ahead
- Daily tide curve with the current time marked
- Rising or falling status and a countdown to the next high or low
- Up to three favorite stations with their next tide at a glance
- Feet or meters, 12-hour or 24-hour time
- Export favorites and settings as a JSON file
How to read a tide table
Why there are usually two highs and two lows
Tides are long, slow waves driven mainly by the Moon's gravity, with the Sun adding a smaller pull. Most of the US East Coast has a semidiurnal tide: two highs and two lows of similar size each day, roughly 12 hours and 25 minutes apart, so the times slide about 50 minutes later every day. Much of the Gulf of Mexico has a diurnal tide with only one high and one low on many days. The West Coast, Alaska and Hawaii have mixed tides — two highs and two lows that can be very different in height, which is why a curve is more useful there than the numbers alone.
What the heights mean
US tide heights are measured from a reference level called Mean Lower Low Water (MLLW): the average of the lowest low tide of each day over a 19-year period. A height of 0.0 ft is that average lowest level, so a negative low (for example -1.2 ft) means the water will drop below it. Minus tides are the ones tide-poolers and clam diggers watch for.
Spring and neap tides
Around new and full moon the Sun and Moon line up and the range between high and low is largest — spring tides, which have nothing to do with the season. Around the quarter moons the range shrinks — neap tides. If you look a few weeks ahead you will see the daily range grow and shrink in roughly a two-week rhythm.
Using the tide for fishing and the beach
Many anglers prefer moving water — the hours either side of a high or low — because current carries bait past fish. Slack water near the turn is usually best for diving and easiest for paddling in narrow channels. For tide pools, plan to arrive an hour or so before a low and leave as the water starts to rise. Remember that predictions describe water height, not current; at an inlet the current can turn well after high or low water.
Why the real tide can differ
Predictions are calculated from long records of astronomical tides. They cannot include weather. A strong onshore wind or a storm surge can raise the water well above the prediction; offshore wind and high air pressure can hold it lower. Heavy river flow changes levels in estuaries. Treat any prediction as a plan, then look at the water and check local conditions and official sources before you rely on it.
Frequently asked questions
Where does the tide data come from?
The predictions are requested from NOAA's public tide prediction service when you open a station and date. The station list itself is built into the app, so search and the map work instantly.
Why are times shown in the station's time zone and not mine?
Tide times are published in the station's local time, including daylight saving time. Marevia shows them exactly as published, so a Hawaii or Alaska tide reads the same as it would on a local tide table, wherever you are.
Where are my favorites and settings stored?
Only in this browser on this device, with no account and no server copy. Clearing your browser's site data deletes them, and they do not sync to another browser. Use Export in Settings if you want a copy.
Do I have to share my location?
No. Location is only used if you tap Use my location on the Near me tab, and only to sort stations by distance. Search and the map work fully without it.
Why is the curve smooth but not exact?
On the web the daily curve is drawn between the predicted highs and lows. It shows the shape of the day well; use the list for exact times and heights.
What does the phone app add?
The iPhone and Android apps can send tide alerts before a high or low tide, and their Premium option adds unlimited favorites and alerts, a monthly view and a six-minute interval curve at stations that support it.
Limitations of the web version
- Tide alerts are not available on the web, because a browser tab cannot send reminders after it is closed
- The web version keeps up to three favorite stations
- The monthly view and the six-minute interval curve are only in the phone apps
- An internet connection is needed the first time you load predictions for a station
Disclaimer
Tide predictions are for general planning only and are not for navigation. Actual water levels can differ from predictions because of wind, air pressure, river flow and storms. Always check official NOAA sources, nautical charts and local conditions before going on or near the water.
Phone app
Marevia is also available as an app for phones and tablets: