Photo: Jakob Owens / Unsplash
Cocos Island
Cocos Island (Isla del Coco) is an uninhabited Costa Rican national park roughly 550km (342 miles) off the Pacific mainland, reachable only by liveaboard. The draw is pelagic action, above all schooling scalloped hammerheads that gather over seamounts and at cleaning stations in the hundreds. It is not a reef or macro destination; you dive a handful of pinnacles and rock islets for big animals in current, not coral gardens. Two seasons shape the trip: the rainy season (June to November) brings nutrient upwellings, stronger currents, rougher crossings and the biggest hammerhead schools, plus the best odds for whale sharks and mantas; the dry season (December to May) brings calmer seas and clearer water but generally less dramatic aggregations. Access is committing: a crossing of about 36 hours each way, and standard trips run 10 to 12 days with three dives a day. Water is 24 to 30 degrees C at the surface but thermoclines can drop sharply, and currents are moderate to very strong. Operators typically want Advanced Open Water plus 50 to 100 logged dives and comfort with current, surge and negative entries. Nothing is guaranteed, but hammerheads are seen on most dives across the year.
What makes it special
- Scalloped hammerhead schools of 100 to 500+ over seamounts such as Bajo Alcyone and at cleaning stations
- Whale sharks in the late rainy season, mostly July to October, over the same seamounts
- A compact cluster of around 20 pinnacle and rock-islet sites, most within a short tender ride
- Manuelita's south side is one of the few reliable places to watch whitetip reef sharks hunt en masse at night
Price range
$$$
Trip length
10–12 days
Diver level
Advanced open water
Trip type
Liveaboard
Price is per person for a typical trip, excluding international flights ($$$ = over $4,000).
A 10-night Cocos liveaboard commonly runs roughly $5,500 to $7,000+ per person, excluding international flights and typically excluding the national park fees. Costa Rica's SINAC charges a park/diving fee of about $70+ per day per diver at the Cocos Marine Conservation Area, so the mandatory park charge for a standard trip adds several hundred dollars (reported around $500+ for a week of diving). Exact fee figures vary between operators and years; confirm at booking.
Best time to dive
- Current
- Strong
- Water temp
- 20–28°C (coldest Aug, warmest Jan)
- Visibility
- 12–30m — Commonly 12 to 30m. Clearer in the dry season (December to May); often reduced to around 10 to 25m in the rainy season due to plankton blooms and runoff. Thermoclines can also cut visibility and temperature abruptly.
- Getting there
- Demanding — Liveaboard only, with a 36h open-ocean crossing to reach the diving.
- Experience
- Advanced in practice. Operators commonly require Advanced Open Water plus about 50 to 100 logged dives, use of a surface marker buoy, and experience with strong current, surge and negative entries. Many recommend Nitrox.
Nearest airports
- SJO — Juan Santamaría International Airport (San José) (International arrival point; from San José it is a road transfer of roughly 1.5 to 2 hours to the port of Puntarenas, where Cocos liveaboards board. Puntarenas is a seaport with no airport of its own.)
Permit required
Cocos Island is a national park and marine conservation area managed by SINAC; all diving is via licensed liveaboard operators, and a park/diving fee is levied per diver per day.
SINAC park and diving fee of roughly $70+ per diver per day (reported figures vary by operator and year; one operator cited about $554 for seven diving days). Usually not included in the headline liveaboard price. Confirm the current amount at booking.
Marine life
Sightings are never guaranteed — the bars show typical likelihood by month.
| Month | Likelihood |
|---|---|
| January | occasional |
| February | occasional |
| March | occasional |
| April | occasional |
| May | occasional |
| June | occasional |
| July | occasional |
| August | occasional |
| September | occasional |
| October | occasional |
| November | occasional |
| December | occasional |
Seen through both seasons but more associated with the nutrient-rich rainy season (June to November). Sources do not give a sharp monthly peak, so coded occasional rather than a specific peak.
| Month | Likelihood |
|---|---|
| January | occasional |
| February | occasional |
| March | occasional |
| April | occasional |
| May | occasional |
| June | occasional |
| July | occasional |
| August | occasional |
| September | occasional |
| October | occasional |
| November | occasional |
| December | occasional |
Reported as increasingly common at Cocos in recent years, seen mainly on the outer sites such as Manuelita Outside and Dirty Rock and around Dos Amigos, more often in the rainy season. Not a reliable sighting on any given dive.
| Month | Likelihood |
|---|---|
| January | rare |
| February | rare |
| March | rare |
| April | rare |
| May | rare |
| June | occasional |
| July | peak season |
| August | peak season |
| September | peak season |
| October | occasional |
| November | rare |
| December | rare |
Encountered in the rainy season, June to November, with the best odds roughly July to September over the same seamounts. Never guaranteed and largely absent in the dry season.
| Month | Likelihood |
|---|---|
| January | commonly seen |
| February | commonly seen |
| March | commonly seen |
| April | commonly seen |
| May | commonly seen |
| June | commonly seen |
| July | commonly seen |
| August | commonly seen |
| September | commonly seen |
| October | commonly seen |
| November | commonly seen |
| December | commonly seen |
Large schools of jacks and trevally are a consistent feature around the seamounts and arches year-round, often massing thick enough to shade the reef.
| Month | Likelihood |
|---|---|
| January | commonly seen |
| February | commonly seen |
| March | commonly seen |
| April | commonly seen |
| May | commonly seen |
| June | commonly seen |
| July | commonly seen |
| August | peak season |
| September | peak season |
| October | peak season |
| November | commonly seen |
| December | commonly seen |
The marquee species. Schools are seen over seamounts and at cleaning stations across the year; sources agree the largest aggregations, sometimes 100 to 500+ individuals, form in the late rainy season, roughly August to October. IUCN lists the species as Critically Endangered.
| Month | Likelihood |
|---|---|
| January | commonly seen |
| February | commonly seen |
| March | commonly seen |
| April | commonly seen |
| May | commonly seen |
| June | commonly seen |
| July | commonly seen |
| August | commonly seen |
| September | commonly seen |
| October | commonly seen |
| November | commonly seen |
| December | commonly seen |
Seen year-round at cleaning stations and seamounts such as Dirty Rock and Punta Maria, with large individuals reported around 3 to 3.5m.
| Month | Likelihood |
|---|---|
| January | commonly seen |
| February | commonly seen |
| March | commonly seen |
| April | commonly seen |
| May | commonly seen |
| June | commonly seen |
| July | commonly seen |
| August | commonly seen |
| September | commonly seen |
| October | commonly seen |
| November | commonly seen |
| December | commonly seen |
Common in the blue water around the island and near seamounts on most dives across the year, often gathering under the boat between dives.
| Month | Likelihood |
|---|---|
| January | occasional |
| February | occasional |
| March | occasional |
| April | occasional |
| May | occasional |
| June | occasional |
| July | occasional |
| August | occasional |
| September | occasional |
| October | occasional |
| November | occasional |
| December | occasional |
Associated with a specific cleaning station (Silverado) south of Chatham Bay; not a general sighting across most Cocos dives. No strong seasonal pattern in the sources.
| Month | Likelihood |
|---|---|
| January | occasional |
| February | occasional |
| March | occasional |
| April | occasional |
| May | occasional |
| June | occasional |
| July | occasional |
| August | occasional |
| September | occasional |
| October | occasional |
| November | occasional |
| December | occasional |
Regularly reported at cleaning stations and along ridges such as Dirty Rock and Punta Maria, often in small groups. No strong seasonal pattern in the sources.
| Month | Likelihood |
|---|---|
| January | occasional |
| February | occasional |
| March | occasional |
| April | occasional |
| May | occasional |
| June | occasional |
| July | occasional |
| August | occasional |
| September | occasional |
| October | occasional |
| November | occasional |
| December | occasional |
Seen year-round around the rocks and at cleaning stations such as Dirty Rock. Hawksbills are also reported but less often.
| Month | Likelihood |
|---|---|
| January | occasional |
| February | occasional |
| March | occasional |
| April | occasional |
| May | occasional |
| June | occasional |
| July | occasional |
| August | occasional |
| September | occasional |
| October | occasional |
| November | occasional |
| December | occasional |
Reported year-round on sand and reef edges, including around Dos Amigos and Pejora. No clear seasonal pattern in the sources.
| Month | Likelihood |
|---|---|
| January | commonly seen |
| February | commonly seen |
| March | commonly seen |
| April | commonly seen |
| May | commonly seen |
| June | commonly seen |
| July | commonly seen |
| August | commonly seen |
| September | commonly seen |
| October | commonly seen |
| November | commonly seen |
| December | commonly seen |
Abundant year-round. Manuelita's south side is known for large numbers hunting together on night dives, one of the signature experiences at Cocos.
Dive sites
Worth knowing before you book
- Liveaboard-only, with an open-ocean crossing of about 36 hours each way that is frequently rough; not for the seasickness-prone.
- Expensive and time-consuming: standard trips are 10 to 12 days and $5,500 to $7,000+ per person before flights and park fees.
- Nothing is guaranteed. Hammerheads are seen on most dives but school size and whale-shark, tiger-shark and manta encounters vary and are never promised.
- Currents are moderate to very strong with surge, thermoclines drop sharply, and negative entries are common; unsuitable for newer or nervous divers.
- Rainy season delivers the biggest aggregations but also the roughest seas and the lowest visibility, so the best animal odds and the most comfortable conditions rarely coincide.
Sources & last checked
Checked July 2026
This is a researched draft, not yet human-verified. The seasonality and logistics are drawn from the sources below — confirm specifics (permits, fees, closures) with an operator before you book.
- Best Time to Dive in Cocos Island — Liveaboard.com
- Cocos Island Diving, Costa Rica — Dive The World
- A Guide to the Dive Sites of Cocos Island — Aqua-Firma
- Cocos Island Liveaboard Diving Guide — Costa Rica Spirit
- Cocos Diving Trips, Costa Rica - Frequently Asked Questions — Dive The World
- San Jose Airport (SJO) to Puntarenas - Private Shuttle Van Service — Two Weeks in Costa Rica
Note on the data: Site coordinates are approximate positions near the island, not surveyed dive-site GPS. Park fee figures differ noticeably between sources and years and are given as ranges. Hammerheads are coded reliable year-round with a late-rainy-season peak because sources agree schools are present all year but largest roughly August to October. Water temperature: Surface temperature is fairly stable year-round (roughly 26-29C with little seasonal change), so maxC tracks the surface; minC reflects Cocos's pronounced thermoclines, which below about 25m routinely drop 3-6C into the low 20s (and occasionally into single figures on strong days), so the min band is thermocline low rather than surface. Access: Liveaboard-only and the most remote of this group: fly into San Jose (SJO), transfer roughly 1.5-2 hours to the port at Puntarenas, then a weather-dependent open-ocean crossing of about 36 hours to reach the island. Independently verified 2026-07-20 (confidence high).