Expert divers tell that Sipadan Island has one of the best underwater in the world ! It's true !! Sipadan underwater is amazing...stupefying...unequalled ! During scuba diving you could meet plenty of sharks, Barracudas,Bluespotted Stingray, LionFishes, Bigeye Travelly fishes, Clown Fishes, Parrot fishes and...and...a spactacular coral reef !
Equipment: As everybody know Sipadan island is actually accessible only by private scuba diving center ! So you should leave from Semporna or Mabul Island to go to Sipandan ! Mabul Island is a quite beautiful tourits island. It's full of holiday camps clean and beautiful but very very expensive. One of the most popular and cheap is Mabul resort: 350 ringit for person for night diving and equipment included. The boat trip from Mabul to Sipadan is 30 almost minutes. Another way to reach sipadan is to sleep in Semporna and go to a scuba diving center that provides a Daily Dive & Snorkle trips to Sipadan, Mabul, Kapalai and another 20 more islands. You'll spend almost 40 minutes. The cost is about 250 ringit, for 2 people, for a daily trip everything included (equipment, lunch, guide, boat trip).
I suggest to leave from Semporna and plain everything with Scuba Junkie (a scuba dive center runs by a group of nice britain people.
The thing why going to Sipadan is diving!!! Diving is program on that island. You have 3 bootdives a day and you can do as many dives off shore as you like. The housereef is the best I've ever seen! 600m drop off!!! You can be lucky and see everything from gostpipe fish to hammerhead shark.
Equipment: Got to bring your equipment! You can rent the one from the dive center, but you know. It's not your own and sometimes not in best shape. trust me i saw people underwater...