Pulau Weh is a fantastic place to dive. It's a squiggly island about one hour north, by ferry, from Banda Aceh. The best sites are in Gapang Bay, which is a protected area on the north side of the island. It is full of life. And it's staggeringly beautiful.
I've spent a lot of time in cold places, and diving had never crossed my mind. But you can't live in a place with such fabulous underwater beauty and NOT take advantage of it. Luckily, I had a good friend, an expert diver, who hooked me up with a great dive shop: Lumba Lumba (which means "dolphins" in Indonesian). So I learned to dive. Definitely one of the better decisions I've made in my life.
I took several courses and am now a certified rescue diver. When I started the rescue course, I had no idea I would be moving to Mongolia. I actually studied some of it in Ulaanbaatar, during a pre-assignment visit, in subzero temperatures.
After finishing the course, I went on a 50-meter dive to see a sunken German ship, the Sophie Rickmers, from World War II. On my last dive in Aceh, I took photos. It was a bit awkward, but I managed to get some good shots. One of them, of an anemone fish, has become my thumbnail for Facebook, Twitter, Posterous, and other networking sites.
Shortly after I finished the rescue course (which, by the way, is NOT easy), I found myself in Ulaanbaatar. I cannot dive here. But there is incredible natural beauty in Mongolia, and I am learning to enjoy it.