Poole’s beaches all look much the same in a photograph and are not remotely the same in practice. Here is the honest comparison.
Sandbanks: the famous one
Wide, clean sand on the spit guarding the harbour mouth, with Blue Flag status in many years and RNLI lifeguards through the season. Full facilities. Also the busiest: car parks fill by mid-morning on any hot day, and the roads out to the peninsula become a slow loop of cars hunting for the same space. Come early or take the bus. See Sandbanks Beach.
Shore Road: the same sand, fewer people
Running west from Sandbanks along the bay, with beach huts and promenade access. Identical water, easier to reach.
Canford Cliffs and Branksome Chine: the shaded option
Reached down wooded chines cut into the cliff, which gives you shade on the walk and filters out some of the crowd. Branksome Chine has a café, facilities and parking in the chine itself. See Branksome Chine Beach.
Branksome Dene: the quiet one
Usually the emptiest of the bay beaches, with fewer facilities and, on parts of it, year-round dog access. If the others are full, come here.
Hamworthy Park: the one for toddlers
The important one, and the one visitors miss. Hamworthy faces into the harbour rather than out at the open sea, so the water is shallow, calm and warmer. There is grass, a playground and a paddling area behind the sand. For under-fives it beats Sandbanks comfortably. See Hamworthy Park Beach.
And one place not to swim
The harbour entrance between Sandbanks and Studland drains and fills a 36-square-kilometre harbour twice a day. The tide runs hard through that narrow gap and the chain ferry crosses it constantly. Swim on the bay beaches, between the flags. See beach safety.
The free bit
All of it. The beaches cost nothing; only the parking does. See the full beaches guide.