Arco Iris, Brumel Island - Caribbean Coast
Arco Iris, off Brumel Island, is a site we keep coming back to on Costa Rica's Caribbean side. It’s not about endless visibility, averaging 10m, but what you find within it. We love pushing past the initial drop, tracking the rock formation that snakes north from the island’s northwest face. This is where the action happens. Our favourite dives here are early morning, before the currents pick up too much. You often catch glimpses of white tip reef sharks patrolling the deeper edges, sometimes so close you hear their tails swish past. Keep an eye out for the smaller stuff too: the flash of a Rainbow Scorpionfish against the coral, or a curious Beaubrummel peeking from a crevice. We’ve spotted Bloody Frogfish here, clinging perfectly camouflaged. It’s a site that rewards slow, deliberate diving, especially for those who appreciate the hunt for the unusual alongside the larger marine life. Arco Iris is best for divers who enjoy a bit of current and thrive on discovery rather than wide-angle vistas.
- Location
- Caribbean Coast, Costa Rica, Central America
- Coordinates
- 10.512900, -85.824900
- Type
- reef
Marine Protected Area: Marino las Baulas de Guanacaste
Best Time to Dive in Caribbean Coast
The warmest water temperatures in Caribbean Coast occur in March, averaging 29.8°C. The coolest conditions are in November at 27.6°C.
Monthly Water Temperatures
- January: 28.9°C
- February: 29.6°C
- March: 29.8°C
- April: 29.6°C
- May: 29.1°C
- June: 28.4°C
- July: 28.6°C
- August: 28.5°C
- September: 28.5°C
- October: 28.1°C
- November: 27.6°C
- December: 28.4°C
Nearby Dive Sites in Caribbean Coast
- Arco Iris, Brumel Island (cave)
- Arrecife Conway (reef)
- Bajo Del Diablo
- Bajo del Diablo Deep
- Bajos Castañones (reef)
- Barco Hundido (wreck)
- Bloody Reef (reef)
- Bocas Dive Center
- Bocas Diving Pirates
- Brumel deep (reef)
- Brumel deep
- Brumel shallow
- Brumel shallow (reef)
- Cabeza de Mono
- Cadena (reef)
Nearest Dive Centres to Arco Iris, Brumel Island
Marine Life in Caribbean Coast
Home to 218 recorded species including 198 reef fish, 11 hard corals, 5 whales & dolphins, 3 other, 1 seagrass & algae.
Notable Species
- Sleeper (Gobiomorus maculatus) - Reef Fish
- Lesser Starlet Coral (Siderastrea radians) - Hard Corals
- Barred Livebearer (Poeciliopsis turrubarensis) - Reef Fish
- Cowfish (Tursiops truncatus) - Whales & Dolphins
- Lettuce Coral (Agaricia agaricites) - Hard Corals
- Spotted Sleeper (Eleotris picta) - Reef Fish
- Lamarck's sheet coral (Agaricia lamarcki) - Hard Corals
- Pointed Pencil Coral (Madracis asperula) - Hard Corals
- Green Turtle (Chelonia mydas)
- Bridled Dolphin (Stenella attenuata) - Whales & Dolphins
- Mustard hill coral (Porites astreoides) - Hard Corals
- Giant goby (Gobiomorus dormitor) - Reef Fish
- Mulet (Mugil curema) - Reef Fish
- Scroll Coral (Agaricia undata) - Hard Corals
- Yellowtail Parrotfish (Sparisoma rubripinne) - Reef Fish
- Barber (Acanthurus bahianus) - Reef Fish
- Elkhorn coral (Acropora palmata) - Hard Corals
- Blue Doctor (Acanthurus coeruleus) - Reef Fish
- Graham's sheet coral (Agaricia grahamae) - Hard Corals
- Sleeper (Eleotris amblyopsis) - Reef Fish
Recommended Packing List for Arco Iris, Brumel Island
Based on average water temperature of 28.8°C, currents 3 cm/s.
- Shorty or Rashguard - warm 29°C water needs minimal exposure protection
- Mask - essential for every dive
- Fins
- BCD - buoyancy compensator
- Regulator - your most safety-critical piece of gear
- Dive Computer - tracks depth, time, and NDL
- Surface Marker Buoy (SMB) - essential for boat pickups
- Dive Torch - useful for crevices and colour at depth
- Underwater Camera - capture your diving memories