KK or kota kinabalu, a really interesting place located in north of borneo with kind of european look and wide, clean streets, cafes, bar, cinemas good public transportation linking the whole city.
I was there in 2010, and was very surprised with such developed city before landing there all I thought it'd be another south asian big town like few in thailand no infrastructor.
GUESS I WAS WRONG !!! the place is really cozy with a good night life and you can exlpore it all on foot.
kk has nice zoo where you can see local animals including the malay tigers, a big museum that tells the history of saba, shops carrying the big names like channel, billabong and many more.
from kk you can take a min bus and go to other districts of Borneo "don't forget to take your passport with you" because of border controls.
if you wanna go diving in mabul, sibuan & sipadam, you have to go to a weird but exotic at the first glance called semporna that's the only link from KK to the island.
the ride from kk to semporna takes about 10 to12 hours, or you can take other routes and do pit stops in some small towns and check them out!! but not very worth!
semporna does not have hostels the deal is you get there, go to mabul island, on the island YEAH there dive centers offering cheap accomodation. you can also shop aournd in town for budget dive resorts. IT'S A PLACE FOR DIVERS, mainly.
there is jungle tour like the one I did where in sipalok where I saw the probosians monkeys, crocodiles on the river banks , huge bats they look like the size of a cat!!!
on mabul fi you have a chance to dive in the back of the island is AMAZING!!! mage size turtles, nudi branchs which I saw only exit on the dive magazine pages. extremly crystal clear water!!!! some strong currents some times
sibuan is kinda similar to mabul, but at as good as !!! there was where I saw my first mandarin fish:)
sipadam good place for dive, nice place to spot white trips lying on the bottom of the sea,pumping water through their gills
diving in sipadam is not as easy as diving int he similans, for sipadam there's a waiting list and the a bit pricy!!!!!!!! but really worth!