Dive Site: Ulloa and Lobster Rock

About Ulloa and Lobster Rock

Ulloa and Lobster Rock are twin dive sites on Cocos Island, frequently explored together due to their close proximity. This area, known for its volcanic rock formations and unique topography, provides a dynamic environment for divers. The dive site features a significant plateau located north of Lobster Rock, blanketed in Rhodolith, a red algae resembling coral. This unique habitat is home to the endemic Cocos rosy-lipped batfish, a rare sighting. Sandy flats surrounding the main rock formations house nesting triggerfish, flounders, and various eels. While sheltered from strong surface conditions, currents can be swift, requiring divers to be mindful during ascent. The site is a reliable alternative when other, more exposed Cocos sites are challenging. It's renowned for abundant whitetip sharks receiving cleaning services, alongside schools of reef fish, cottonmouth jacks, and surgeonfish. Afternoon dives often reveal spawning black triggerfish and convict tangs, with occasional visits from tiger sharks, manta rays, and silvertip sharks. Accessed by tender from liveaboards, divers typically start at one end and conclude at the other, maximizing their exploration of both Ulloa and Lobster Rock. The varied terrain and rich biodiversity make this a compelling dive for observing both resident reef life and passing pelagics.

Dive site facts: Ulloa and Lobster Rock

Depth

15–30 m

Current

Can be swift

Visibility

15–30 m

Water temperature

22–27 °C

Entry

Tender

Level

Advanced

Dive type

Reef, big_animals, cleaning_station

Night dive

Not permitted

Region / port

Cocos Island

Coordinates

7.7984° N, 86.2452° W

Conditions & Currents

Currents at Ulloa and Lobster Rock can be swift at times, particularly impacting ascent, although the site is generally sheltered from strong surface conditions. Divers may experience some drift, which necessitates good buoyancy control and careful monitoring of dive profiles. Thermoclines are common, with water temperatures ranging from 22 to 27 degrees Celsius. Visibility typically ranges from 15 to 30 meters but can fluctuate due to plankton blooms, which also attract large pelagics. Entry and exit are conducted via tenders from liveaboards. Divers should be proficient in managing currents and prepared for potential temperature drops at depth.

Marine life & sighting chances

Whitetip reef shark

common

Cocos rosy-lipped batfish

occasional

Cottonmouth jacks

common

Surgeonfish

common

Black triggerfish

Afternoon · common

Convict tangs

Afternoon · common

Rays

occasional

Flounders

occasional

Snake eels

occasional

Garden eels

occasional

Tiger shark

occasional

Manta ray

occasional

Silvertip sharks

occasional

Goby (cleaning fish)

common

Dive profile & how the dive runs

Dives at Ulloa and Lobster Rock typically begin with a tender drop-off. Since the sites are close, divers often start at one and finish at the other, making a transit between them. The dive usually commences by exploring the volcanic rock formations, with a focus on schools of reef fish and whitetip sharks at cleaning stations. Divers will progress to depths between 15 and 30 meters, navigating around the structures and checking sandy flats for endemic species and eels. A key area to visit is the Rhodolith-covered plateau to the north, looking for the Cocos rosy-lipped batfish. In the afternoons, divers may observe black triggerfish and convict tangs spawning at the base of Lobster Rock. Attention to current is important, as it can be swift, particularly during ascent. The safety stop will be conducted in shallower, calmer waters before surfacing for tender pick-up.

Underwater photography

Ulloa and Lobster Rock offers both wide-angle and macro opportunities. For macro subjects like the endemic Cocos rosy-lipped batfish, nesting triggerfish, or various eels in the sandy flats, a 60mm or 100mm/105mm lens is essential. External strobes are highly recommended to bring out the vibrant colors of reef fish and the Rhodolith formations. For wide-angle shots, such as schools of cottonmouth jacks, surgeonfish, or the abundant whitetip sharks, a rectilinear wide-angle lens would be suitable, especially with good visibility. Be prepared for potential thermoclines and swift currents, which necessitate good buoyancy control to maintain stable shots. When photographing spawning fish or the elusive batfish, maintain a respectful distance and avoid disturbing their natural behavior.

Combine with nearby dive sites

• Ulloa

  Often combined with Lobster Rock

• Chatham Bay

  Nearby for checkout dives and macro

• Manuelita Outside

  Known for pelagic sightings and cleaning stations

• Manuelita Coral Garden

  Protected site for macro and reef fish

• Dirty Rock

  Popular rock formation with diverse marine life

• Submerged Rock

  Pinnacle with arch, whitetip shark nursery

Getting there & logistics

Cocos Island is a remote, uninhabited national park located 340 miles southwest of Costa Rica, accessible exclusively via liveaboard. Divers fly into San Jose (SJO) at least one day before their cruise departs. Operators arrange transfers from San Jose to Puntarenas on the Pacific Coast, where liveaboards embark for a 36-hour journey to Cocos Island. Trip lengths are typically 10 nights. All diving at Cocos is conducted from tenders, with up to four dives per day. There are no night dives permitted. Park fees are usually included in the liveaboard package, but divers should confirm. Due to its remote nature and potentially challenging conditions, Cocos is recommended for experienced divers.

Safety & environment

Cocos Island is a remote destination, and the nearest recompression chamber is on mainland Costa Rica, implying a significant evacuation time. Comprehensive dive insurance, including coverage for emergency medical care and evacuation, is mandatory for all divers. Divers must be advanced and experienced, comfortable with strong currents, deep dives, and open-ocean conditions. All dives are conducted from tenders. The site can experience swift currents during ascent, requiring divers to manage their buoyancy and air consumption effectively. Thermoclines are common, necessitating appropriate exposure protection. Night diving is not permitted at Cocos Island to preserve the pristine marine environment and ensure diver safety.

Who it suits — and who it doesn't

FAQ

Ulloa and Lobster Rock FAQ

Liveaboards diving Ulloa and Lobster Rock

These liveaboards may visit Ulloa and Lobster Rock on selected itineraries — the exact dive sites depend on departure, weather and conditions.

Cocos Aggressor

Costa Rica

22 guests37.8 m

$477/day

Sea Hunter

Costa Rica

20 guests

$690/day

Okeanos Aggressor II

Costa Rica

24 guests36.6 m

$582/day