

Best for beginner divers, 5-19m, boat entry, mild current.
W Arch is a cave site located off Irabu Island, Japan, featuring a distinct arch structure that creates sheltered, low-light zones. Divers can explore depths ranging from 5 to 19 metres, with an average depth of 12 metres. The site is accessible by boat and is suitable for beginner divers due to the mild currents. Visibility typically ranges between 15 and 30 metres. Water temperatures remain warm throughout the year, varying from 23 to 30 degrees Celsius. Divers should be aware of lionfish sheltering within the cave structure and along shaded ledges, and maintain buoyancy control to avoid contact with the substrate.
24.86540, 125.15920
Lionfish shelter inside the arch and along shaded ledges, so keep your hands away from the walls and watch where you fin. A guided tour is a smart choice here as local guides know exactly where the nudibranchs and longnose hawkfish are sitting on any given day.
Boat entry.
Recorded nearby, within 20km
Depth
5-19m
Visibility
15-30m
Skill Level
Beginner
Entry
Boat
Boat required
Water Temp
23-30°C
Current
Mild
Typical Dive
45 min
Divers may encounter lionfish sheltering in the cave and along ledges. Other life includes crabs, shrimps, crustaceans, nudibranchs, and longnose hawkfish found on coral outcrops near the arch opening.
Yes, the site is suitable for open-water certified divers due to the mild currents and manageable depths.
The site ranges from 5 to 19 metres in depth, with an average depth of 12 metres.
W Arch is a boat dive; a boat is required to reach the site.
Water temperatures range from 23C in January and February to 30C in August, remaining warm throughout the year.
Diving at W Arch in Irabu Island requires the following certifications: Open Water. Always dive within your training limits.
A 3mm wetsuit is recommended for diving at W Arch in Irabu Island. Water temperatures range from 23°C to 30°C.
Divers at W Arch in Irabu Island should be aware of lionfish. These encounters are generally rare and avoidable with proper awareness. Follow local safety guidance and maintain a respectful distance from all marine life.