I would concentrate on Coral Bay. Nice small dive op friendly, helpful, as enthusiatic about the marine life as the paying customers! Not over controlling and regimented. Prices reasonable. Between the 2 dive sites spent over an hour with a pod of humpbacks, saw dugongs, and tiger shark between dive sites as well. Exmouth on the other hand is over priced, regimented, controlling DM's just pretty awful. Navy pier is good but the saga kind of spoils it. 2 hour brief in a classroom, followed by much passport checking, crowded dive site, sargeant major dm just over the top, oh I forgot 4 typed pages of waivers and releases etc to sign. Almost guarateed a raggy (grey nurse in Oz). Having dived Aliwal Shoal at night and day, have seen "schools" of raggy's, so the one that we returned to 3 times on the dive was so so. For a shore entry dive own gear and rental tank $170.00. Unfortunately you can only do Navy Pier with Ningaloo Dreaming. I asked about a dive and snorkel with whale sharks trip 1 dive plus snorkel $430.00 per person!! (ie close to $1500.00 for a family of 4, just giggled hysterically when they confirmed this was the going rate) I found Exmouth over priced and overhyped. Coral Bay was just magic, only 1 dive shop can't miss it.