Marmion Marine Park, stretching 20km north of Perth, offers world-class snorkeling in protected waters with crystal-clear visibility averaging 15-20 meters. The real magic? Swimming directly with playful Australian sea lions at Seal Island who are genuinely curious about humans.

Best Snorkel Sites: Boyinaboat Reef (perfect for beginners, 2-3m depth, easy entry), Little Island (intermediate level, 3-6m with incredible coral gardens), and Seal Island (advanced, sea lion encounters guaranteed). Water temperature ranges 17-24°C seasonally — A 3mm wetsuit works year-round.

Getting There: Train to Clarkson Station, then Bus 471 to Hillarys Boat Harbour ($7.60 total using SmartRider card). Gear rental at Hillarys Dive Centre costs $35/day for mask, fins, snorkel, and wetsuit.

Timing is Everything: Early morning 7-9am offers best visibility and calmest conditions before afternoon sea breezes kick in. Sea lions are most active during incoming tides — Check tide charts before heading out. The juvenile sea lions at Seal Island are incredibly playful and will often swim circles around snorkelers.