Sargassum seaweed now washes up on Caribbean beaches by the tonne, some winters more than others. Battigia shows the risk on a map of the whole region, and answers the two questions a traveller has: is February a bad month for Punta Cana, and what does it look like this week?

• 61destinations, from Cancún to Guadeloupe
• 24,600stretches of coast of about 5 km
• dailyfrom NOAA satellite data

The coastline, coloured by risk

The Caribbean, the Gulf of Mexico, Florida and northern South America, in four levels — low, warning, medium, high — plus grey where clouds hid the sea that day. Every colour comes with its label and its own symbol, never colour alone. Touch a coast and the nearest destination opens.

A destination’s page

The worst level on the coasts within 25 km, and the share of coast at each level; the last few days, to see which way it is going; and a “When to go” calendar that counts, month by month, the days at each level since July 2025. Links to the official bulletins where they exist (Météo-France for Guadeloupe, Martinique, Saint-Martin and Saint-Barthélemy), and directions in Apple Maps.

Your trips, and a reminder before you leave

Add a destination and dates, or let the trips you planned in Bivio and Cartina appear on their own. A few days before departure — three by default — a notification gives you the risk where you are going. It is computed on your phone; no server sends it.

A widget, and two things to ask Siri

“My beaches” shows today’s risk at your favourites. Siri can tell you the risk at a destination, or at your next trip.

A regional risk, and the app says so

The data is an experimental product of NOAA and the University of South Florida, computed from satellite images: a risk for a stretch of coast, never a forecast for one beach. Many hotel and town beaches are cleaned every morning. Battigia is affiliated with neither organization, and every screen shows the date of the data.

What leaves your phone

The app downloads the whole map of the risk from a relay of ours and tells it nothing about you — not your location, not your destinations, not your trips. Matching a place to its coast happens on your phone. The privacy page names every connection.

Seven languages, nine variants: English, French, German, Spanish (Spain and Latin America), Italian, Japanese and Portuguese (Brazil and Portugal). Free, with no in-app purchase.

Battigia is being tested and has not been submitted to the App Store. There is nothing to download yet — this page will carry the link when there is.