If it's not too late, here's my two cents on this question.
I've been living and working in Jakarta, Indonesia for the last four years, and have dived a number of the areas in the country (Komodo, Sumba, Manado, Java, Bali, Lombok, Donggala in Central Sulawesi). The Sangalaki trip, done last August for a week, was one of the best.
My group stayed at the Sangalaki Dive Lodge. Prices were fair and the island had nesting turtles at night (Mandatory electricity off in most areas of the resort past 6pm as the turtles won't come inland if lights are on). During one of the nights, I got woken up from some serious noises, which turned out to be a huge turtle throwing sand back into the hole it had just used to deposit eggs. We also caught three episodes of turtle hatching, and watched the little tykes scramble out of the sand into the sea.
The mantas were awesome. Sangalaki, I think, is fairly known for its all black, as opposed to the black on top and white below, manta rays. There were plenty of sharks as well, especially around the cleaning stations that the mantas frequented. As it is in East Kalimantan, Sangalaki also has tons of nudibranchs.
A trip to Kakaban is not to be missed. The jelly lake (four different species of non-stinging jellyfish) is pretty interesting, but the best part of Kakaban is definitely the hammerhead dives. Strong sideway currents on a slope that descends to 30 metres, and then drops into a sheer wall. The currents were strong enough on the 4 dives the group did at that site, and we cruised down to the wall areas and caught some hammerheads about 20m to the blue water. It's not a "schooling" experience, but it was still awesome enough to watch the small groups of hammerheads lazily cruising against the current as we humans struggled.
Getting there was a bit of a journey though, as we had to change planes four times from Jakarta, and sit on the small boat to the island for two and a half hours.
If you choose Sangalaki Dive Lodge, ask for Andreas for dm, and say hi to Kadek.
I booked through
www.sangalaki.net
Office Address: Wisma Sabah, Grd Floor Lot 28
Postal Address: P.O Box 16360, 88000 Kota Kinabalu, Sabah, Malaysia
E-mail:
nadia@sangalaki.net,
azmi@sangalaki.net,
info@sangalaki.net
Tel: 60-88-242336
Fax: 60-88-238336