Pontoon/Platform
Many day-cruise operators travel to permanent moorings in the form of a platform or pontoon. These can be quite elaborate with tables and chairs, shade and fresh water showers, just like visiting a floating island on the reef. They allow easy access into the water for diving, snorkelling, swimming and other reef activities. You can even sleep overnight on one in the Whitsundays!
Underwater Observatory
There are underwater observatories on Green Island off Cairns and on Hook Island in the Whitsundays. These let you watch and learn about marine life in the wild while staying dry!. Some of the pontoons out at the reef also have purpose built observatories so you can follow the snorkellers and divers along with the fish.
Glass Bottom Boat / Semi-Submersible
If you want to see eye to eye with some of the marine life without getting wet, try a semi-submersible or a glass bottom boat tour. The semi-submersible sits deeper in the water with glass side panels while the glass bottom boat skims across the surface; great for shallow coral areas.