형제섬 (Hyeongjeseom)

Verified2026-09-30 checkedReef

Two small islands off Sagye, and the gentlest boat dive on Jeju.

Depth: 8–25 m26–82 ft
Difficulty: Beginner
Entry: Boat
Typical current: Light
Coordinates: 33°12.318′N 126°20.598′E
Activities: Scuba · Freediving · Snorkelling

Hyeongjeseom — the Brother Islands — lie a few hundred metres off Sagye on Jeju's south-west coast, under Sanbangsan. The bottom is boulder and sand at 8 to 25 m with light current and no wall to fall off, which makes it the island's usual first boat dive and its usual night dive. Soft coral is patchier than at Munseom but the fish life is the same, and the short crossing means it runs on days when the south-east sites do not.

Ten minutes by boat from Sagye harbour, an hour from Jeju City by road.

Best season

ExcellentAug–Sep
GoodJun–Jul
GoodOct

Conditions

Water temperature: 25.9°C79°F
Wave height: 0.3 m1 ft
Air temperature: 19.2°C67°F
Wind speed: 11.7 km/h7.3 mph

Updated 2026-10-07 18:45 UTC · Source: Open-Meteo

Weather data by Open-Meteo.com (CC BY 4.0)

Conditions are reported for information only. Assess the site yourself and follow your guide and your training.

No live conditions for this site yet.

We only show numbers we can attribute to a source.

Sea state and tide

On a date

Tide · 10/8

Low02:01-0.44 m
High07:531.17 m
Low14:03-0.71 m
High20:221.44 m

Forecast heights against mean sea level. Real tides in a bay, a harbour or over a flat can differ — check an official tide table before you get in.

Pick a day to see its tide

Only wave height and wind are scored, because those are what close a boat ramp or a shore entry. Water temperature is reported and never scored: 12°C is an ordinary dive in a drysuit and punishing in a 3 mm, and a number that cannot see your suit has no business marking it down. Stars do not decide whether you get in — you and your guide do, on the day.

Weather data by Open-Meteo.com (CC BY 4.0)

Marine life you may see

Soft coralDendronephthya spp.Common
Striped beakfishOplegnathus fasciatusCommon
Korean rockfishSebastes schlegeliiCommon
Pearl-spot chromisChromis notataCommon
NudibranchNudibranchiaCommon
Giant morayGymnothorax javanicusSeasonal
Moon jellyfishAurelia auritaJun–SepSeasonal

From divers

What people who were in the water reported. Not a forecast, and not a judgement about whether the site is safe to dive.

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