Big Tunnels
Dive site at a Cayman Islands Department of Environment public mooring off Grand Cayman. Here's what has been recorded at this site month by month, how the region’s reefs have weathered ocean heat, and how to prepare.
Big Tunnels: dive site at a Cayman Islands Department of Environment public mooring off Grand Cayman.
Entry
Shore and boat entries vary by site. We list only rules we can cite from official sources; entry points, depths and currents will be added once we can verify them.
- The DoE has installed public moorings to protect reefs from anchor damage. Use a mooring instead of anchoring whenever possible; it is an offence to damage coral anywhere in Cayman waters. Cayman Islands DoE · Public Moorings
- The maximum stay on a public mooring is 3 hours. Do not use moorings in winds of 25 knots or more. Cayman Islands DoE · Public Moorings
- Marine Park zones carry their own rules (for example, no taking of marine life in Marine Reserve zones and no SCUBA diving in No Diving zones without permission). Check the zone with the DoE app or brochures. Cayman Islands DoE · Marine Parks
- Wildlife Interaction Zones are the only places in the Cayman Islands where you may legally feed or interact with marine life. Cayman Islands DoE · Marine Manners
At this sitegeotagged 743 m from the site coordinates Zombie Crab (Gecarcinus ruricola) · Dan Schofield · CC BY 4.0 · iNaturalist
[video slot · coming soon]
The surface noise falls away.
Reds go first. The world turns blue-green.
Then Big Tunnels rises to meet you.
What lives here, by month
Pick a month. These are the species most often recorded within about a kilometre in that month, from open survey records.
Most-recorded species, all months
- Flamingo tongue snail (25)
- Lined sea hare (17)
- Tritonicula hamnerorum (15)
- Ocean Triggerfish (14)
- Lettuce slug (14)
- Bermuda shrimp (13)
- Banded-antennae squat shrimp (10)
- Stoplight Parrotfish (10)
- Sailfin Blenny (9)
- Bar jack (9)
- French angelfish (9)
- Yellow stingray (9)
- Elysia cornigera (9)
- Queen Angelfish (9)
- Great barracuda (9)
- Banded clinging crab (8)
- Great Star Coral (8)
- Mutton snapper (8)
- Foureye butterflyfish (8)
- Yellowline Arrow Crab (8)
GBIF.org (2026-10-14), occurrence records within ~1 km, licensed CC0 or CC BY 4.0 only. Birds and land animals are excluded. Counts reflect survey effort, not abundance. 879 qualifying records. See them on GBIF. Common names: Wikidata (CC0) / GBIF. Species photos: Wikimedia Commons, credited with each species.
Forty-one summers of heat
Each stripe is one year since 1985, colored by its peak heat stress across NOAA's “Cayman Islands” region. These are NOAA Coral Reef Watch satellite figures for the whole region, not for this one site.
Heat stress, measured from orbit.
NOAA CRW virtual station “Cayman Islands”. NOAA's alert thresholds are 4 °C-weeks (Alert Level 1) and 8 °C-weeks (Alert Level 2). Station page · Method. Credit: NOAA Coral Reef Watch.
Conditions
Average sea temperature through the year. Check the live readings before you go.
Average sea surface temperature by month: NOAA CRW “Cayman Islands” station climatology (monthly means).
Buoy readings are measurements; forecasts are models. Use them for planning only, and assess conditions on site. Depth and visibility data aren't listed until we can cite a source.
Plan & prepare
- Read the official marine forecast the night before.Offshore, wind and sea state decide the day.
- Check the cited local rules above and pay any park fee before you dive.[Placeholder: verified operator list to come]
- Study this month's species above.You'll recognise more when you know the names.
- Hands off, fins up, buoyancy dialled. Log what you see.Your sightings can become tomorrow's open data.
Photographs from Big Tunnels
Openly licensed photos, each checked for location against its title, description, category or geotag. Labels show how close each one is to the site.
Credits
- Coordinates
- Cayman Islands DoE public moorings 2023 (WEST), mooring "Big Tunnels" · source · government publication. Cayman Islands Department of Environment, Public Moorings (updated January 2023). Each site uses the coordinates of the named public mooring.
- Species records
- GBIF.org, CC0 & CC BY 4.0 records. By license: CC_BY_4_0: 861, CC0_1_0: 18
- Dataset
- iNaturalist Research-grade Observations · doi:10.15468/ab3s5x (777 records) · GBIF
- Dataset
- EOD – eBird Observation Dataset · doi:10.15468/aomfnb (96 records) · GBIF
- Dataset
- Birda - Global Observation Dataset · doi:10.15468/6kud7x (4 records) · GBIF
- Dataset
- CAS Invertebrate Zoology (IZ) · doi:10.15468/tiac99 (2 records) · GBIF
- Query
- https://api.gbif.org/v1/occurrence/search?decimalLatitude=19.358266999999998,19.378267&decimalLongitude=-81.426517,-81.406517&license=CC0_1_0&license=CC_BY_4_0&taxonKey=44&taxonKey=206&taxonKey=229&taxonKey=136&taxonKey=225&occurrenceStatus=PRESENT&limit=0
- Heat stress & SST
- NOAA Coral Reef Watch, 5 km Regional Virtual Station “Cayman Islands”
- Hero photo
- At this sitegeotagged 616 m from the site coordinates Spotted Spiny Lobster (Panulirus guttatus) · Dan Schofield · CC BY 4.0 · iNaturalist
- Arrival photo
- At this sitegeotagged 743 m from the site coordinates Zombie Crab (Gecarcinus ruricola) · Dan Schofield · CC BY 4.0 · iNaturalist
- Gallery
- 5 photos, credited under each image
- Species photos
- Wikimedia Commons, credited with each species. Full list: Data & sources