Is February Izu's Best Month? IOP 17.7m, Ito 17.4m Winter Data

Think winter diving is just about enduring the cold? In reality, February delivers some of the best visibility of the year in the Izu area. Water temperatures drop to 15-16°C, requiring a drysuit, but in return you get visibility 1.5 times greater than summer. Here is the data every diver should see.

February Visibility Data for the Izu Area

What IOP's 17.7m Means

IOP's February average of 17.7m represents a 5.4m improvement over its August average of 12.3m. Winter visibility is over 1.4 times greater than summer. For underwater photographers, this difference is transformative -- backgrounds are crystal clear at greater distances, and the blue of the ocean is more vivid.

January vs February: Which Is Better?

Our January analysis showed that January records the highest annual visibility at many sites. February is slightly lower, but the difference is typically less than 1m. February does have some advantages:

• Longer daylight: More daylight than January, giving more flexibility for afternoon dives
• Milder air temperatures: The coldest snaps of January have passed, making surface intervals more comfortable
• Long weekends: Japan's National Foundation Day (Feb 11) creates a 3-day weekend opportunity

Drysuit Necessity

At 15-16°C, a 60-minute dive in a wetsuit carries a real risk of hypothermia. A drysuit is strongly recommended. Many dive shops offer drysuit rentals, so check in advance if you don't own one.

If you are unfamiliar with drysuit operation, consider a practice dive before committing to a full winter diving day. Buoyancy control differs significantly from wetsuit diving and requires some adjustment.

Why February Izu Diving Is Special

1. Outstanding visibility: 17m+ clarity opens up the underwater landscape
2. Peak nudibranch season: Winter to spring brings the greatest nudibranch diversity
3. Lumpfish (Dango-uo): A winter-only macro favorite, best seen in February-March
4. Uncrowded: Far fewer divers than summer, even at popular sites
5. "Izu Blue": With minimal plankton, the ocean takes on a deep, vivid blue unique to winter

Summary

• IOP's February visibility (17.7m) is about 1.4x its summer average (12.3m)
• Ito at 17.4m and Koganezaki at 15.7m also near annual highs
• Water temperature of 15-16°C requires a drysuit
• Slightly lower than January but with longer days and milder air
• Winter-exclusive marine life including nudibranchs and lumpfish