Getting Certified as an Advance Diver was a great decision !!!
I did it in Kota Kinabalu, with Borneo Action Dive Center .
One of the best dive shops, I've been to yet. The equipment is kept in perfect order, the staff is very friendly and outgoing - all diving fanatics from various corners of the globe. Full set of PADI courses on offer at reasonable prices (I even took my Rescue Diver there) - instructors are dedicated to teaching the skills rather than just push you through the course (as is unfortunately the case with many dive joints in tourist-frequented areas).
Dive trips are a full-day-out to one or two of the five islands of TAR Marine Park and include 2 dives + full equipment rental. There is ample opportunity to take a snorkelling tour, during your surface rest between dives. The divemasters are well-versed in the ways of the local marine life and excellent guides.
As an added bonus, Jeffrey Hong is an underwater photographer, able to add some great shots of your underwater adventures to your picture album.
Last and best of all, the staff is not partial to a happy night-on-the town after a hard day's diving. Two thumbs up!