Hammerhead and Thresher Sharks Spotted in the Waters Around Tokyo’s Islands!

You won’t believe the hidden treasures waiting beneath the waves near Tokyo! The city isn’t just a bustling metropolis—it’s also the gateway to some of Japan’s most unexpectedly captivating seas, home to fascinating creatures like hammerhead sharks, thresher sharks, and dragon moray eels. Just a 30-minute flight—or a direct jet ferry ride taking as little as 1 hour and 45 minutes from the city center—transports you to a wild, untamed ocean world you’d never expect to find so close to Tokyo. Ready to dive in?

The Sharks Divers Love—And Where to Spot Them Near Tokyo

When people think of Tokyo, few imagine it as a world-class diving destination. But that’s only because its hidden treasures are still waiting to be discovered. Tokyo’s remote islands—especially Oshima Island (also known as Izu Oshima)—boast rich waters teeming with sharks that divers from around the globe come to see.

On Oshima Island, you have the chance to encounter hammerhead sharks and copper sharks. You might expect that seeing these creatures would require countless dives—but the waters around Oshima are something else entirely.

Even Open Water Divers Can Spot Hammerhead Sharks on Oshima Island!

With ideal diving conditions, Oshima Island offers divers the chance to explore its underwater world at a relaxed pace—especially when hoping to encounter iconic species like hammerhead and thresher sharks—without having to battle strong currents.

What truly sets Oshima apart is the rare opportunity to observe hammerhead sharks without the need for drift diving. Instead of being swept along by powerful currents, divers can stay in one spot, fully immersing themselves in the vibrant marine environment. It’s the perfect choice for those seeking a more controlled and serene diving experience—one that still delivers the excitement of encountering large, majestic marine life. That’s why even open water divers can try their luck at spotting sharks around Oshima Island.

When Can You See Hammerhead Sharks in Oshima?

On Oshima Island, hammerhead sharks can be seen from July through October, with September and October being especially ideal. As the summer crowds begin to fade, it becomes easier to book boats and accommodations—and the weather is more pleasant as the intense heat gives way to milder conditions.

These incredible sharks typically appear in the early morning, with an impressive 80% chance of a sighting. Watching hammerheads glide gracefully through the water is an awe-inspiring experience—and a guaranteed highlight of any diver’s adventure.

Thresher Sharks Make Their Appearance in Fall!

It’s astonishing to encounter the elusive thresher shark—a species found in only a handful of locations worldwide—in the waters near Tokyo. Underwater photographer Kirin Sekito, who has explored dive sites across the globe, including the Galápagos Islands, was stunned when he came face-to-face with a thresher shark off Oshima Island.

“To think that such a remarkable creature can be found in a sea just 1 hour and 45 minutes from central Tokyo—this is truly a rare place, even by global standards,” he said.It’s astonishing to encounter the elusive thresher shark—a species found in only a handful of locations worldwide—in the waters near Tokyo. Underwater photographer Kirin Sekito, who has explored dive sites across the globe, including the Galápagos Islands, was stunned when he came face-to-face with a thresher shark off Oshima Island.

“To think that such a remarkable creature can be found in a sea just 1 hour and 45 minutes from central Tokyo—this is truly a rare place, even by global standards,” he said.

When Can You See Thresher Sharks in Oshima?

While thresher sharks can potentially be spotted year-round around Oshima Island, sightings are most likely in the fall—especially in October and November. These elusive sharks tend to appear on cloudy, overcast days, adding a bit of mystery to the experience. With a 50% chance of encountering one, why not try your luck and see if you can spot one for yourself?

Just a Short Trip from Tokyo—And You Can Be Diving the Same Day!

One of Oshima’s greatest appeals is its easy access from central Tokyo. Unlike destinations that require a flight—where diving on the first day is usually off-limits—Oshima can be reached by ferry, allowing you to dive the very same day you arrive.

For travelers on a tight schedule, that’s a major advantage. Even with limited time, you can still enjoy a full diving experience without missing a beat.

Seasonal Splendor Beneath the Waves: Explore Oshima Anytime!

The waters surrounding Oshima Island are teeming with life, thanks to the warm Kuroshio Current that flows through the region. Divers can encounter a vibrant array of tropical fish typically found in southern seas, alongside larger marine creatures like sharks—a major draw for many visitors.

Oshima’s volcanic origins further enrich its underwater allure. The seafloor is shaped by dramatic natural formations, including lava arches and striking columnar joints, creating a dynamic and visually stunning landscape. These geological wonders add an extra layer of excitement to every dive, offering unforgettable sights for both novice and seasoned divers alike.

What truly sets Oshima Island apart is its ever-changing underwater seasons. Just like on land, the ocean here transforms throughout the year, offering fresh and unique experiences for divers in every season.

In the summer months, divers may spot graceful green sea turtles gliding through the warm waters alongside sharks. In winter, the seafloor transforms into a mesmerizing scene as purple-hued Kagikenori seaweed blankets the ocean floor, creating a surreal underwater landscape. Year-round, fascinating creatures like moray eels and lionfish continue to captivate divers, no matter the season.

It’s this rich marine biodiversity and ever-changing seascape that keep divers coming back to Oshima year after year.

Oshima’s Shore Diving: Stay Under Longer Than You Can with Boat Dives

While many dive destinations around the world emphasize boat diving, Oshima is renowned for its beach diving—offering a unique set of advantages. Unlike typical boat dives, which tend to be shorter, beach dives around Oshima allow for extended underwater time—often 40 to 50 minutes—providing ample opportunity for relaxed exploration and underwater photography.

Another perk of beach diving here is the easy access to captivating dive sites, many of which are just a short walk from the shore. For those venturing farther out, some local dive shops offer underwater scooters, making it effortless to glide through the currents without expending too much energy. The result is a more comfortable, leisurely dive that lets you conserve strength while fully enjoying the wonders of Oshima’s underwater world.

Recommended Diving Shops on Oshima Island

Oshima is home to many top-tier dive shops, offering exceptional experiences for divers of all skill levels. However, only a few are equipped to accommodate non-Japanese speakers. If you don’t speak Japanese, it’s important to choose a dive shop where you feel welcome and at ease. Below, we introduce a few dive shops on Oshima Island known for their friendly, English-friendly service and warm hospitality toward international visitors.

Yellow Dive https://tokyoislands.jp/post/activities/diving-and-guesthouse-yellow-dive

Orange Fish https://tokyoislands.jp/post/activities/orange-fish-oshima-island

And more… https://www.oshima-diving.org/english.html

Tips for Scuba Diving on Oshima Island

If you’re planning to go scuba diving on Oshima Island, here are a few key tips to keep in mind.

1. Take a Ferry to the Island

Although flying to Oshima might seem convenient—it takes only about 30 minutes—it’s not ideal for divers. Flying shortly before or after diving increases the risk of decompression sickness, meaning you won’t be able to dive on the same day you arrive. Instead, opt for a large ferry or a high-speed jet ferry. This allows you to travel safely and start diving later that same afternoon.
Check out detailed access information here: https://tokyoislands.jp/post/page/access

2. Avoid Staying Near Mt. Mihara

When booking accommodation, avoid places near Mt. Mihara due to the risk of decompression sickness caused by the altitude. Instead, look for lodgings near Motomachi, Okata, Senzu, or Habu Port.
If you're unsure about where to stay, feel free to reach out via the Tokyo Islands contact page or consult with your diving shop.

3. Dry Suits Are a Must in Winter and Spring

Water temperatures on Oshima Island can get quite chilly:

• Winter: around 15–18°C
• Spring: around 15–21°C

So, you'll definitely need a dry suit during these seasons. In summer and fall, temperatures usually range from 18–27°C, so a wetsuit is often sufficient. If you're bringing your own suit, it's a good idea to check the latest water temperature with your diving instructor in advance.

4. You Can Dive with Just a 1-Night, 2-Day Trip!

If you're short on time, don't worry—you can enjoy diving on Oshima Island with just a 1-night, 2-day trip. Take a high-speed jet ferry in the morning to arrive on the island, and spend the afternoon diving or exploring local sights.

In the summer or fall, if you’re hoping to see hammerhead sharks, plan for an early morning dive the next day. You can still fit in up to two more dives afterward if you book a return trip on an afternoon jet ferry.

5. Be Flexible—Ferries and Flights Can Be Canceled due to Bad Weather

Although Oshima Island is officially part of Tokyo, it remains a remote destination accessible only by ferry or plane. While ferry services boast a high operation rate—over 90%—transportation can still be disrupted during typhoon season or in poor weather conditions. To avoid unexpected issues, be sure to leave some flexibility in your schedule before and after your island trip, just in case of delays or cancellations.

6. More Than Just Diving—Explore the Natural Wonders of This Volcanic Island

Oshima Island is a volcanic gem rich in natural beauty. From dramatic crater views and massive fault lines to untouched forests and seasonal sights like the vibrant red camellia fields in winter, the island offers breathtaking scenery year-round.

You’ll also find local cuisine unique to the island, adding even more flavor to your trip. Even if you’re here for the diving, don’t miss the chance to explore beyond the ocean!
Check out more about sightseeing on Oshima Island here: https://tokyoislands.jp/oshima

All underwater photos are taken by the photographer, Kirin Sekito