I'm planning to go to Semporna again via bus from tawau and it led me to this thread.
I went there the first time last year, stayed at Dragon Inn and then Arung Hayat in Mabul. I love Arung Hayat travel lodge, it's a decent place for budget traveller and most importantly they serve nice food. My friend just went there again early this month and agree that their food is good.
I came with another friend that time and took the RM95 minibus/van ride from airport - Semporna town. It's a decent airconditioned van and we had a pleasant ride.
I'm a diver and i have dived in Mabul area and also islands from Semporna IE: Timba-timba, Pandanan, Mataking..etc.
I can say that Mabul - Kapalai has aloooot of fish and bigger fish than peninsular malaysia islands..as for corals..go for islands like Timba2, Mataking there..not much fish but amazing corals..
As for snorkelling, i dont think u can see much there, unless if u're lucky..u can see turtles (most of the time can see when diving), school of cuttlefish, etc..which is not bad, from my experience..but u have to be patient.
I went there after being a diver for 1 year and i enjoyed the dive sites very2 much. In the early days of diving, i dont enjoy so much as i'm still getting used to the skills..so..I really don't think getting a license there would be good as you might not be able to enjoy the dive so much..especially going to Sipadan..if u can wait till you're confident and comfortable underwater..110%!
I haven't been to Sipadan coz of some mess made by my agents on the permits..so if u can get a diveshop with guaranteed permit! I do not regret it so much as it's my first time there..i end up doing more dives than i planned! (planned for 9 dives inc Sipadan, became 16 dives in Semporna/Mabul, which is an unforgettable experience).
As for seafood, i'd highly recommend rabbit fish!! please dont forget to try that fish when u're in Semporna. I have 1 seafood restaurant which serves very nice food not far from Seafest Hotel, but i cant remember the restaurant name!!
If u come from the jetty/Dragon Inn, pass by Seafest..walk further more u can see a row of shop and this nice airconditioned restaurant. Surprisingly their price is not has high as u think it would be!