Hi there, Sipadan is good for the barracuda tornado, giant sea turtles, pelagics, panoramic seascapes, there is a lot of beaufitul corals and many sea turtles just at 5m depth (beautiful seascapes in natural light). Mabul and Kapalai are excellent for macro (ghost pipefish, frogfish of all kind, pygmies, flamboyant cuttlefish, nudis, octopus, and a lot of juvenile). At low tide at night, can just walk around in 50 cm depth and photograph a lot of macro and juvenile critters. Layang Layang is good for hammerheads during the mating season (march-may), staying a week in a a minimum as it's only accessible via charter flight. Mataking and surrounding islands are good for macro. Lankayan is also good for macro. Not all the resorts on Mabul have Sipadan permits. The recommended ones are: Seaventures (they have a dorm option), SMART (mid range at good prices), Borneo Divers, MWB (luxury on stilts), Mataking (they have guaranteed Sipadan permits but are further away). There is only one Sipadan liveaboard, the Celebes Explorer. Advantage is that it's possible to dive almost everyday at Sipadan. If you stay 2 weeks, a good combination is either Sipadan (stay on Mabul) and Mataking or Sipadan and Layang Layang if it's during the hammerhead mating season. Best season for visibility at Sipadan is March till July. July is busy touristic season so the best time is March till June. 1st week of may is also busy, so not recommended. The malaysian riggint has dropped a lot since last year, meaning the usd streches a lot more and there are good deals to have all year round at the mid-range resorts.