Most resorts in Tulamben and on the northeast coast run their own boats and PADI operations. The best dives are early morning or night dives during the full moon.
Being on Bali's northeast coast, Tulamben Bay receives very plankton-rich waters from the Indonesian Throughflow (the major ocean current that moves from the Pacific to the Indian Ocean). This, coupled with the different physical environments found in the area, means the bay contains a stunningly diverse underwater ecosystem.
The 120m (394-ft.) U.S. Army Transport Liberty shipwreck lies 20m (66 ft.) offshore and offers an extraordinary density of marine life, including a huge school of big-eyed trevally, bumphead parrotfish, leaf scorpionfish, and pygmy seahorses. If you go night-diving, look out for the flashlightfish, Spanish dancers, and cephalopods.
Both the Coral Garden (which runs eastward from the Liberty shipwreck) and the upper area of the Wall/Drop-off (at the eastern end of the bay) provide wonderfully shallow dives where you're limited by air supply rather than bottom time, and yield an incredible variety of marine life from Thecacera nudis to boxer crabs to frogfish and ribbon eels in all stages of development. Deeper on the Wall/Drop-off are reef sharks, sponges, and gorgonian fans (one of 3m/10 ft. diameter), and occasional sightings of whale sharks and Mola-Mola.
Slightly north of Tulamben is Kubu, where conditions always seem to be calm. Here you'll also sight plentiful gorgonians, bommies with beautiful soft corals, and scores of nudis. Five minutes eastward by outrigger, Batu Kelebit is where you are most likely to see pelagics including -- on rare occasions -- dolphins. Further east, Batu Niti has the area's most pristine corals.
Due to the beach entry, Tulamben is also great for snorkeling and for the 1-day introduction to diving offered by some dive companies (although you need booties and open-heeled fins, not full-foot fins for walking on the rocky beach).
Contact Scuba Seraya Dive, 5 minutes south of Tulamben Bay in the Scuba Seraya Resort (tel. 0361/283922; fax 0361/281347; www.scubaseraya.com; two shore dives US$75, three shore dives US$90 per person). If you're coming from the south, contact AquaMarine Diving, Jl. Raya Petitenget 2A, Seminyak (tel. 0361/738020; fax 0361/738021; www.aquamarinediving.com; US$75 in Tulamben, US$85 outside Tulamben per person).
Another Shipwreck -- Both divers and snorkelers will find the Japanese shipwreck off Banyuning worth a visit. It is possible to wobble in from the rocky beach or hire a local fishing boat and enter the water that way. Under the trees on the beach, a small warung serves cold drinks, beer, juice, and decent local food. You can hire snorkeling gear from your hotel or from the outfitters on the beach in front of the shipwreck.
Avoid the Underwater Crowds -- Because many PADI companies are now organizing day trips to Tulamben from the south, the dive sites are overcrowded after 11am. To avoid the crowds, plan to stay overnight and dive early in the morning or late in the afternoon.