Actually this is not the case. When I was diving the Galapagos we constantly saw more whalesharks at 5m than we did at deep levels. Along with the whalesharks we also saw Galapagos Silky sharks and a massive school of Galapagos hammerhead that completely covered the seabed.

Ningaloo reef offer many more snorkelling excursions than they do diving...they even have spotter planes that go up to look for the whale sharks. BUT if you are diving they guarantee sightings where as snorkelling it is by chance.

The other location that is also amazing is Christmas Island (the Australian Territory one). After the whales sharks leave Ningaloo they head to XCH before then heading back down south.

Fiji has the shark dive - yes it is touristy but they have tigers and bull sharks on a regular basis. There is also then the chance to see some amazing reefs also.

Cheers
FF