The only operator licensed to take people to Penguin Island near Rockingham, this outfit also runs other low-impact tours. The most popular is the dolphin swim (per person $205 to $225), which lets you interact with some of the marine park's 200 wild bottlenose dolphins. Swimming with dolphins can disturb them, so an alternative is the two-hour dolphin-watch tour (adult/child $85/50).
There's also a 45-minute penguin and sea-lion cruise in a glass-bottomed boat. Pick-ups can be arranged from Perth hotels.