Brr — diving in Atami in winter


As any scuba diver knows, when the diving itch hits, you just gotta scratch. But what if the itch strikes in midwinter when you have neither the time nor funds to fly to a tropical resort? Not to worry. Not only is it possible to dive around mainland Japan in the winter months, it can even be done on a day trip from Tokyo. What’s more, underwater visibility is better in the winter; the weather is more stable; and there are no crowds.

Last fall, in the throes of a midlife crisis, I decided to do one of those things I’ve always wanted to do — learn to scuba dive. Although people tend to associate scuba diving with tropical places like Thailand and the Maldives, Japan is also a good country for diving. It’s a narrow archipelago with 34,000 km of coastline and more than 2,000 diving points, which means no one has to travel very far to dive.

So, two weeks after my 46th birthday, I was certified as an open-water diver after completing a course on Ohshima, an island that is a popular diving spot less than two hours from Tokyo by high-speed boat. One of the things I learned is that it’s important to dive frequently to maintain your skills. I was enthusiastic to dive often anyway, but it was already mid-September, and I didn’t have much time before the cold weather set in.

The main diving season around mainland Japan is July to November, when the ocean is at its warmest. In October, I did two more dives on Ohshima. In December, I did a little diving while on a family vacation to Australia. But then it was January; I was back in Tokyo, and it seemed like an awfully long time to wait for July to come round to dive again.

That’s when I found out that it’s possible to dive locally, even in winter. The ocean is colder, but you can dive if you wear special protection called a “dry suit.” I’m so new to diving I didn’t realize there’s something of a mystique to dry suits, and that many people think dry suits are too difficult for novices. It’s probably just as well I didn’t know, because I was getting cold feet as it was.

The problem is that I hate being cold. I’m a middle-aged mom who wears socks to bed. What was I thinking, signing up for a dive in late January? The night after I made the reservation, I had a nightmare about turning to ice in the ocean. I woke up — you guessed it — in a cold sweat.

But there was no way I was going to wimp out. So early on a Saturday morning, I left my apartment with a backpack full of warm clothes. Less than two hours later, I was gearing up in Atami, a seaside resort on the eastern side of the Izu Peninsula in Shizuoka Prefecture.

I made my arrangements with Japan Underwater Explorers/TokyoScuba, a Tokyo-based international diving operation that actively promotes winter diving by offering dry-suit trial dives. Manager Thomas Jonsson met me at Atami Station and provided me with all the gear I needed, including a brand new dry suit manufactured by DUI of San Diego, California. I considered myself pretty lucky to be having my first dry-suit experience in the TLS 350, the same suit used by elite military divers like the U.S. Navy SEALs. Thomas would teach me the skills I needed to use a dry suit and be my guide underwater.

Most people are familiar with wet suits, which get their name because you get wet while wearing them. Water enters at the wrists, ankles and neck and gets trapped between your skin and the snug material of the suit. Your body heats the trapped water, and you stay warm longer because heat radiates more slowly through the suit than from bare skin.

A dry suit, on the other hand, is watertight and fits loosely except for tight seals at the neck and wrists. It keeps you dry, but it doesn’t keep you warm, so you need to wear warm garments underneath. You also create an air space within the suit to provide extra insulation and prevent the water pressure from squeezing the suit around you. You inflate the suit via a hose attached to your air tank, and release air through exhaust valves built into the suit.

The only tricky thing you have to do when using a dry suit is add and release air to equalize the pressure inside it as you are diving. When you descend, the weight of the water above you puts pressure on the trapped air and compresses it. At that point, you have to add air into the suit or you’ll feel squeezed and cold. When you go back up, the water pressure decreases, allowing the trapped air to expand. This can cause you to rise faster than is safe for your body. So, during an ascent you have to release air from your suit.

We started out in a small, private marina owned by YGM, an Atami diving operation that provides services to divers including boat rides out to the dive sites. The water temperature was 15 degrees. The sheltered harbor was a good place for me to refresh my skills and practice using a dry suit, but it isn’t the most exciting dive spot. Nevertheless, in a 20-minute dive, I saw plenty of marine life, including kelp groves, a large hermit crab dragging its shell, a big kawahagi (threadsail filefish) and lots of bearded himeji (goatfish).

When we got out of the water, I was shivering a little. This is not too surprising, given that we had been in the water for about an hour including practice time, but it made me worried. The air temperature was only 8 degrees, and we’d be outside during the entire lunch break. And, it had started to rain. I borrowed a warm jacket, which helped enough so that I stopped shivering, but I never really warmed up. I entertained a doubt or two about the sanity of winter divers.

Fortunately, for the second dive, Thomas lent me his hood, which was warmer than mine. He also reminded me to add air to my suit for insulation. I was a little more encouraged as we rode a boat five minutes outside of the harbor to a dive spot called Bitagane, where we descended 22 meters to an underwater rock outcrop covered with anemones and soft corals. With a thicker hood, more air in my suit and a higher level of activity, I wasn’t cold at all. Visibility was about 10 meters, which is fair for Atami in winter but much better than in summer. During the 35-minute dive through beautiful coral formations, we spotted squirrelfish, boxfish, a colorful sea slug called a nudibranch and several moray eels. At the end of the dive, on our way up, the sun broke through and illuminated the ocean just as we went through a school of shimmering sardines. It was a wonderful finale in an exciting, comfortable dive.

Arranging a winter dive

Japan Underwater Explorers/TokyoScuba organizes dives nearly every weekend throughout the year. On “Dry-Suit Trial Days,” the company waives the 5,000 yen rental fee for a dry suit. Reservations are required. Two guided dives at Atami, including pick-up at the station, lunch and use of showers and changing facilities, costs 18,000 yen. The company organizes dives to many locations and offers instruction and certification in English, Japanese and other languages. Call (03) 3447-0530 or send an e-mail to For more information, visit the Web site at

Getting to Atami

By bullet train, Atami is just 43 minutes from JR Shinagawa and 50 minutes from JR Tokyo Station. One-way fare is 3,570 yen from either station. You can also take a regular Tokaido Honsen train, which makes the trip from Shinagawa in 1 hour, 41 minutes (7 minutes longer from Tokyo Station) and costs 1,890 yen. Information on YGM Harbor including directions is available (in Japanese only) at

It takes about two hours to drive from Tokyo, depending on traffic, and there is parking available for divers.