You might reasonably imagine that "Little sea" and "Seaview" in Weymouth are by the sea. They are not and neither is Rockley Park in Poole. Little sea is by the coastal path but it has a large lagoon (little sea) separating it from the Chesil Bank which is very stoney and partially closed at times to protect nesting sea birds, you need to go into Weymouth for the sandy stuff. It is possible to walk to the beach at Bowleaze Cove from Seaview but its a long way and uphill on the way back.Waterside, as recommended by Ray, is much closer. Rockley Park is a long way inside Poole Harbour. It has a small beach and boating but it is not like the real thing which you will find at Sandbanks or Bournemouth. This may not be important to you but if you want a beach holiday without all the hasle of driving and finding a parking space you may be better to look elswhere, especially at the new inflated Haven prices.