Divers in Cozumel have been counting
sharks for seven years.
743 sightings across 66 dive sites, almost all of them logged on ordinary recreational dives. Every record is public, georeferenced and permanent — an open reef survey anyone can check, and add to.
The origin
It began with a spreadsheet and a dive log.
Since 2019, dive guides, instructors and researchers working out of Cozumel have written down the sharks they met — species, how many, where, and whatever else was worth noting. The fieldwork is led by Mar Sustentable, drawing on the local ecological knowledge of the people who are in the water every day. More than forty dive operations have contributed.
That kind of record is fragile. It lives in one file, in one spreadsheet, under one person's name, and dive-site names drift between logs — the same reef written five different ways. Before anything else could happen, all 743 records were standardised against a catalogue of 87 official sites in the Cozumel Reefs National Park, and every one of them was given real coordinates.
BiodiversityOS is what that record became: open, addressable, and no longer dependent on a single file surviving.
The record
743 sightings, one island, every one of them logged by hand.
Almost all of it was logged on ordinary recreational dives — guides and divers writing down what they saw at the end of a working day, dive after dive, since 2019.
What is out there
Sightings by species. The reef is dominated by two of them; the hammerheads and the whale sharks are the rare days.
- Nurse sharkGinglymostoma cirratum485
- Caribbean reef sharkCarcharhinus perezi186
- Great hammerheadSphyrna mokarran31
- HammerheadSphyrna sp.23
- Bull sharkCarcharhinus leucas11
- Whale sharkRhincodon typus3
When they show up
Sightings by month across every year on record. February is the busiest; June the quietest.
Every record carries its coordinates, date, species, count and the note the observer wrote at the time. Dive sites were standardised against a catalogue of 87 official sites in the Cozumel Reefs National Park, so a sighting logged as “cedral bajo” and one logged as “Paso del Cedral” end up in the same place.
The platform
Data that empowers action.
Every observation becomes a living map of species presence — structured, georeferenced, and open to anyone working to protect the ocean.
Georeferenced sighting map
Plot observations on an interactive map. Filter by species, behavior, and date range to explore distribution patterns.
Scientific integrity
Each observation follows a structured data schema. Community submissions are reviewed to maintain scientific reliability.
Community verification
Local ecological knowledge from fishers and divers is integrated with field research methods developed by Mar Sustentable.
How it stays open
A record is only as good as your ability to check it.
Conservation data usually asks you to trust whoever holds the spreadsheet. This one does not.
Nobody owns the record
Sightings are written to a public registry on Celo. There is no private database to lose, no login to grant, and no administrator who can quietly change what a record said.
Every sighting keeps its author
A record is attributed to the address that submitted it, and only that reporter can correct it. The observation stays credited to the person who was actually in the water.
Check it yourself
Anyone can replay the chain and rebuild the map from scratch. The map is a view of the record, not the record itself — which is what makes it worth trusting.
The network
The people in the water see it first.
A research vessel visits a reef for a season. A dive guide is there four times a week, for years. That difference is the whole point.
Researchers & scientists
Georeferenced sightings with species, counts, depth, dive site and the observer's own field note — downloadable, citable, and free.
Local communities
Dive operations and guides who log what they see, and keep credit for it. The record grows from working days, not expeditions.
Conservation organizations
Seven years of presence data across a national park, by site and by season — the kind of baseline that is usually missing.
Web3 / DeSci community
A live registry with real observations behind it, not a demo. The contracts, the indexer and the app are all open.
Add your observation to the map.
Every sighting deepens our shared picture of marine life. Explore the open data or contribute what you have seen.