The best way to understand Poole is from the water, because the harbour is the thing the town is arranged around.
Harbour cruises and island boats
Boats leave Poole Quay through the season for Brownsea Island, for circuits of the harbour taking in the smaller islands and the shoreline, and for longer coastal runs west past Old Harry Rocks towards the Jurassic Coast. See boat tours for the detail.
Ferries that double as sightseeing
The chain ferry across the harbour mouth to Studland is a four-minute crossing that most people ride for the view. The Channel Islands and France services from the ferry port are a longer proposition: see Jersey, Guernsey and France.
On foot
The Cockle Trail runs through the Old Town, marked in the pavement, and costs nothing. It is the quickest way to read 800 years of trading history off the buildings.