Poole asks a bit more of visitors than the average seaside town, because what makes it special is also what makes it fragile.
Respect the wildlife
Poole Harbour is a RAMSAR wetland and a Site of Special Scientific Interest. Birds roosting on the mudflats at high tide have nowhere else to go, and a walker or a paddleboard that pushes them off costs them energy they need. Keep your distance, and stay off the private islands.
The heath around the harbour is rarer than rainforest and carries ground-nesting birds from spring to late summer. Keep to paths, keep dogs under control, and never light a fire.
Protect the water
Do not anchor on seagrass. Do not swim in the channels or the harbour entrance, where the tide runs hard. Read the beach safety page and swim between the flags where lifeguards are on duty.
Enjoy it properly
Take your litter home, park considerately in residential streets near the beaches, and support the independent businesses that keep the place alive out of season.
See sustainability for the longer version.