Although Sipadan’s seabeds are still among the richest and most beautiful in the world, the island has inevitably suffered from overcrowding in recent years due to its fame and the rampant proliferation of tourist structures on its very limited surface area. Those who first visited and dived Sipadan fifteen years ago could not help but recently notice unmistakable signs of deterioration due solely to human impact. Now that the island has been closed to overnight visitors the situation will hopefully improve soon.

Divers looking for a rustic, relaxed atmosphere similar to Sipadan as it once was, would do well to stay at Pulau Mabul, a small, sandy island a little larger than Sipadan which is less than half an hour’s sail from its more famous sister. This is particularly so if they are interested in the microfauna which is so rare and hard to find at other sites.

Closer to the mainland, Mabul does not offer the steep walls that have made Sipadan famous, and unlike its more famous sister island, its history has deprived it of its original cloak of forests. One quarter of its beaches is occupied by a rather dilapidated kampung (village) of Filipino fishermen who immigrated semilegally, and is entirely covered by a plantation of coconut palms, which makes it look a bit like certain Maldivian postcard islands.

There are four resorts on Mabul: the elegant Sipadan Water Village, jutting out onto the reef with its pilework bungalows, the tranquil Sipadan-Mabul Resort (known as SMART), which is more discreet and hidden among the palms, the funny-looking SeaVentures ex-oil rig anchored in front of the Water Village and the more recent resort built and operated by Borneo Divers. Quite a few for such a small island, in fact.

With few exceptions, the seabeds are decidedly mediocre, at least from the perspective of coral formations. Diving sites are almost all at ridiculously shallow depths (from 2 to 20 meters), often on sandy, muddy or even detrital seabeds. The nearby sandbank of Kapalai, which emerges only during low tide and which hosts a beautiful water village-style resort, offers quite similar seabeds.

Local fishermen also contribute to the impoverishment of marine fauna in the immediately surrounding waters, by fishing along the deep channels that divide the island from Sipadan and the coast in a continuous search for sharks to supply the lucrative Far East market for shark fins. It was not unusual until a few years ago to see the small outrigger canoes used by locals returning loaded with silky sharks, and the occasional tiger shark. Sadly, the sharks are all gone now.

If the picture looks bleak at first, here’s the surprise: Mabul is actually an extraordinary destination for an equally extraordinary variety of rare and spectacular species which are quite difficult to observe during normal dives. These species have extremely specialized behaviors and ecological niches and are highly sought after by photographers who appreciate macrophotography, and more in general by all divers who have learned to appreciate and admire the eccentric, the bizarre, the curious, and even the monstrous.

Mabul is still a “secret” destination reserved for a very few, and it is no accident that the great majority of divers who come to this area, unaware of its treasures, decide to dive at Sipadan. Above all, Mabul and the nearby sandbank of Kapalai are a showpiece of the other aspect of this sea, its third facet - perfectly complementary to the oceanic seabeds of Layang Layang and the teeming, multicolored walls of Sipadan. No connoisseur of the seas of Borneo could consider his explorations complete without a dive on its seabeds.

Every dive holds a surprise or a new species, always rare or at least uncommon, always strange, and always difficult to identify without the aid of the by now highly expert local dive masters, who have truly invented a professional specialization. In the "muck dives" of Mabul and Kapalai, the extraordinary becomes ordinary, and the dense, suspended particles that permanently cloud the underwater horizons transform into a mysterious curtain behind which long sought-after creatures hide, in which the horrifying and wondrous live side by side and merge.

Mabul, whose evening skies witness the passage of flying foxes, and along whose beaches sea snakes Laticauda colubrina crawl under the moonlight, is the underwater kingdom of ornate and robust ghost pipefish Solenostomus cyanopterus and paradoxus, devil scorpionfish Scorpaenopsis and Inimicus, Synanceia stonefish, Odontodactylus mantis shrimps, mandarin fish Synchiropus splendidus and picturatus, blue ribbon eels Rhynomuraena quaesita, snake eels, frogfish, sea horses and crocodile fish - an extraordinary bestiary of eighteenth century monstrosities that seem to belong to the world of fantasy rather than reality.