Most people treat Busselton as a pit stop on the way to Margaret River wine country. Big mistake. About 220km south of Perth, this sunny town on Geographe Bay lets you dive a retired warship, hunt down a picnic with digital clues, and watch whales from a boat, all before you've had a glass of wine.Ready to see what you've been driving past? Here are the top 10 things to do in Busselton, all bookable through WA Holiday Guide.1. Stroll the Busselton Jetty (Then Go Under It)At 1.8km, Busselton Jetty is the longest timber-piled jetty in the Southern Hemisphere, and it has been standing since 1865. Walk it with a coffee in hand, or hop on the little solar-powered train. At the far end, the Underwater Observatory takes you about 8 metres below the surface, with windows onto an artificial reef of corals, sponges and fish. Only six observatories like it exist in the world, so book ahead.2. Spot Whales in Geographe BayFrom late August to around November, the bay becomes a whale nursery. Humpbacks cruise south with their calves, southern rights rest close to shore, and the odd blue whale makes a cameo. Climb aboard with All Sea Charters from Busselton or Dunsborough, or join the eco tours from Naturaliste Charters in Dunsborough, a short drive up the coast.3. Dive a Retired WarshipThe navy destroyer escort HMAS Swan was deliberately sunk off Meelup Beach in 1997 to become a reef. She is 113m long, which gives you a lot of ship to explore. Swan Dive takes certified divers out to the wreck, the jetty and local reefs, and teaches courses from beginner level if you've never breathed underwater.