Reefwander

Pacific Islands · Micronesia

Kosrae

Unbroken hard coral on an island that sees a few hundred divers a year

Kosrae is a single mountainous island at the eastern end of Micronesia with no lagoon, no rivers carrying silt onto the reef and almost no divers — the whole island sees a few hundred a year. The result is hard coral in a state that has become rare anywhere: unbroken plate and staghorn thickets running along a fringing reef that drops from the shallows into deep blue, with visibility that regularly passes 40 m and no current worth the name.

About diving in Kosrae

Days are short-range and boat-based. Operators run small skiffs from the island's two harbours, Okat in the northwest and Lelu on the east side, and because the fringing reef starts close in the ride to a site is rarely long. Which coast you dive is settled at the dock by the trade winds: with no lagoon to duck into, crews work whichever side is in the lee and move around the island as the wind turns. Two tanks in the morning is the usual rhythm, boats back before the rain that this climate delivers most afternoons.

The underwater shape barely changes around the island - a shallow reef flat, a rim where it tips over, a face falling away into open water - and what differs is the angle. Hiroshi Point sits where the reef turns and fish stack along the edge. Walung, on a stretch of west coast the road never reaches, is dived as a slow cruise off the boat that brought you. The Blue Hole is the one site with a route to follow rather than a contour to swim. Little of it needs to be deep: the coral that justifies the trip sits well inside recreational limits, and the wall below is scenery rather than the point.

What you come for is the reef itself rather than encounters. Moorings mean boats do not anchor on the coral, and a dive is spent reading structure - how the plates overlap, where the rim rolls into the drop - instead of waiting for something large to arrive. That makes it an island for wide-angle photographers and for divers content with small lodges, quiet evenings and no dive-town scene. Surface days go to jungle rivers, mangrove channels and the basalt ruins at Lelu, the old seat of the Kosraean kings. Big animals show up, but incidentally.

Best time to dive Kosrae

Kosrae season rating, sea surface temperature, daytime high and rainfall by month, 2011–2025 averages
JanFebMarAprMayJunJulAugSepOctNovDec
SeasonGoodPrimePrimePrimeGoodGoodGoodGoodGoodGoodGoodGood
Sea surface29°C84°F29°C84°F29°C84°F29°C84°F29°C84°F30°C86°F30°C86°F30°C86°F30°C86°F30°C86°F30°C86°F29°C84°F
Daytime high29°C84°F29°C84°F29°C84°F29°C84°F29°C84°F29°C84°F29°C84°F29°C84°F30°C86°F30°C86°F30°C86°F30°C86°F
Rain237 mm9.3 in243 mm9.6 in301 mm11.9 in333 mm13.1 in328 mm12.9 in270 mm10.6 in287 mm11.3 in214 mm8.4 in234 mm9.2 in212 mm8.3 in253 mm10.0 in282 mm11.1 in
Kosrae season rating, sea surface temperature, daytime high and rainfall by month, January to June, 2011–2025 averages
JanFebMarAprMayJun
GoodPrimePrimePrimeGoodGood
Sea surface
29°C84°F29°C84°F29°C84°F29°C84°F29°C84°F30°C86°F
Daytime high
29°C84°F29°C84°F29°C84°F29°C84°F29°C84°F29°C84°F
Rain
237 mm9.3 in243 mm9.6 in301 mm11.9 in333 mm13.1 in328 mm12.9 in270 mm10.6 in
Kosrae season rating, sea surface temperature, daytime high and rainfall by month, July to December, 2011–2025 averages
JulAugSepOctNovDec
GoodGoodGoodGoodGoodGood
Sea surface
30°C86°F30°C86°F30°C86°F30°C86°F30°C86°F29°C84°F
Daytime high
29°C84°F29°C84°F30°C86°F30°C86°F30°C86°F30°C86°F
Rain
287 mm11.3 in214 mm8.4 in234 mm9.2 in212 mm8.3 in253 mm10.0 in282 mm11.1 in

2011–2025 averages. Sea surface: NOAA Coral Reef Watch, measured at the surface, so deeper water can run colder. Daytime high and rain: NASA POWER.

Divable year-round in a wet equatorial climate; Feb–Apr is generally driest and calmest, with little seasonal variation.

Best months: February, March, April

Kosrae water temperature and weather by month

The sea surface stays between 29 and 30 °C (84–86 °F) all year. Rain falls through the year, about 270 mm (11 in) a month on average, with April the wettest. Daytime highs sit around 29 °C (84 °F) all year. The coldest water here is about 27 °C (81 °F), so pack a 3 mm, or even a 2 mm, suit.

Dive types & marine life

The cast is resident rather than seasonal: napoleon wrasse and turtles working the coral, jacks and barracuda holding off the corners, eagle rays crossing the wall, and reef sharks in ones and twos rather than groups. No month is a write-off; the calmer Feb-Apr stretch mainly buys access to the exposed sides, not different animals.

  • Wall
  • Reef
  • Coral garden
  • Drift
  • Night
  • Pristine corals
  • Reef sharks
  • Sea turtles
  • Napoleon wrasse
  • Trevally & jacks
  • Reef fish swarms
  • Eagle rays
  • Barracuda

Best dive sites in Kosrae

Very large hard corals inside 6 m, straight off the beach

to 6 mbeginner

Sharks, barracuda and dog-tooth tuna along a current-swept wall

12–21 madvanced
  • Walung Drop-off

    Western wall falling into blue, thick with plate coral on the rim.

  • Blue Hole

    Sand-floored hole in the reef flat opening onto the outer wall.

  • Yeseng

    Sheltered northern reef used for check dives and night diving.

How to get to Kosrae

The United Island Hopper between Honolulu and Guam is the practical way in, landing at Okat on the northwest coast. Lodges sit along the coast road and run their own day boats; the wide reef flat keeps diving boat-based rather than shore entry. Kosrae observes Sunday strictly, and dive operations generally stand down for it.

Photos from Kosrae

  • François Michonneau · CC BY 3.0

Dive videos

Diving the reefs of Kosrae, Micronesia · Joshua Ptasznyk on YouTube

Kosrae - Walung Dropoff~! · CnC Divers on YouTube

Photo credits

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