I would say the turtle islands, located on the eastern coast of Borneo, a few miles north of Sandakan. Its three main islands and a few smaller ones. Its also a marine park so the turtles are fully protected here
I visited them myself on a trip to Borneo in winter 2005, a ferfect end of the trip after being three weeks on the Bornean mainland.
Its rather easy to get out to these islands as they are located quite close to the coast, we took some speedboats from a small community (dont remember the name), on the way out to the islands you travel through some amazing forests of palm trees and mangrove forest, good birding as well, we probably saw around 20 species of birds on our way out, the higlight was a smaller adjutant walking in the water edge, good place to see saltwater crocodiles (we saw four of them) and water monitors, we saw a monitor on 2,3, impressive sight.
You travel through these forests perhaps 20-30 minutes depending on from where on the mainland you are departing, dont think you can go from Sandakan but I really dont know for sure, but my advice is to go to a smaller harbour or something, and then head out from there.
After the forests its perhaps another 20-25 until you reach Libaran island which is somekind of a gate to these islands which is a marine park, if I remember right you have to stay on this island 24 hours before getting into the of the islands, at least we had to do that becuase of the closeness to the Philippine territory, you cant see the main Philippine islands but a few smalles ones which is a part of the Philippines from here and the waters around Libaran and the island itself is heavly guarded by military boats and armed guards. Libaran is a part of the marine park but not a good spot for sea turtles, I think around 10-15 "land" on this island each year, this is also the only island in the park wich is inhabited, a small community on a few hundred lives here.
I only visited three islands during my visit Libaran, a smaller one of which I dont remember the name, but it was a tiny island, but it had a hatchery (nesting incloaser for turtles) with a few hundred nests, so I guess that sea turtles are visiting that island, we only spend two hourss here, the other snorkled while I was birding, it takes around 20 minutes to walk around the island, birdlife is poor but I manage to see a Collared kingfisher here.
But Selingan island is the place to see large numbers of seaturtles (try to search on google and you will see that its a famous breeding ground for these creatures), you are only allowed to spend two days here as the maximum number of people allowed here on this island is around 50? and its heavily visited so I suggest you look that up.
Most turtles land during the night and you moslty arrives in the middle of the day so its many hours to take a bath, sunbatch, relax or birding.
Birding is supringsly rich here, despite the remoteness, scrubfowl, frigatebird, bulbuls, brahminy kite and green-pigeons is easily seen here, I recorded 20 species here during two days, 14 on the island itself and another 6 seabirds.
I think that two species of sea turtles land on this island, green seaturtle which is very common with around 30 landings per week, hawkbill seaturtle is rather rare with less than 5 landings per week. We saw a totall of three greens and a single hawkbill, the best part was when we realeased hatchlings in the morning
A HIGHLY recommend you to visit these islands, they are simply wonderful.
I will visit them again soon.
