Osezaki
Izu Peninsula · Japan
Osezaki is Izu's crown jewel for macro photography, where a sloping volcanic reef drops to 25 metres and hides extraordinary concentrations of nudibranchs, frogfish, and pygmy seahorses in every crevice. The site's cold, nutrient-rich currents from Suruga Bay keep the water productive year-round, drawing rare critters like hairy frogfish and ornate ghost pipefish. Shore entry and calm conditions make it equally accessible to photographers on a single tank and technical divers exploring the deeper rubble zones.
Conditions
Depth
5 to 25 m
Open water and up
Current
Can be moderate
Can pick up on the edge
Visibility
8 to 15 m
Clearest in the calm season
Water
13 to 28°C
3mm wetsuit
Month by month
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Water (°C) | 14 | 13 | 14 | 16 | 18 | 20 | 22 | 24 | 23 | 20 | 17 | 15 |
| Vis (m) | 10 | 10 | 12 | 12 | 12 | 8 | 8 | 6 | 8 | 12 | 12 | 10 |
| Current | Gentle | Gentle | Gentle | Gentle | Moderate | Moderate | Moderate | Gentle | Gentle | Gentle | Gentle | Gentle |
Your chances of seeing each animal
Moray Eel
Last confirmed Jul 5, 2026 · 7 records
Very likely
Most dives
Verconia norba
Last confirmed Apr 27, 2025 · 5 records
Sometimes
About 1 in 3 dives
Festive Sea Slug
Last confirmed Jul 5, 2026 · 3 records
Rare
Now and then
Spotted White Sea Slug
Last confirmed Jul 5, 2026 · 1 records
Rare
Now and then
Bat-Wing Seaslug
Last confirmed Jun 9, 2024 · 1 records
Rare
Now and then
Sakuraeolis gerberina
Last confirmed Mar 31, 2025 · 1 records
Rare
Now and then
Hairy Frogfish
Expected
Known here, not yet in recent logs
Nudibranch (Flabellina)
Expected
Known here, not yet in recent logs
Gear