Holes Bay is an intertidal embayment off Poole Harbour in the county of Dorset on the south coast of England. It lies mostly within the Borough of Poole and is close to Poole town centre. It is an important wetland bird haven.
Holes Bay lies on the south coast of England within the Borough of Poole, apart from its northwestern shore which is part of Upton. The bay drains the heathlands around Creekmoor and is bounded in the east by Sterte and Stanley Green, in the north by Creekmoor, in the northwest by Upton, in the west and southwest by Hamworthy and in the southeast by the Old Town area of Poole.
Holes Bay is a tidal inland lake which lies to the north of Poole Harbour. It is a designated harbour quiet area. The exit to the bay is a narrow gat between Lower Hamworthy and Poole Old Town, and runs past the RNLI lifeboat station and part of Poole Quay before entering Poole Harbour itself. Spanning the inlet are two bridges: Poole Bridge and the newer Twin Sails Bridge, opened in 2012. Access to Holes Bay for vessels with a draft greater than 2 metres (6.6 ft) is only possible when the bridges are lifted, which occurs at several fixed times daily and sometimes on request. The new bridge is intended to help reduce traffic jams by ensuring at least one bridge is open to vehicular traffic at any one time.
The northern part of the bay is crossed from west to east by the South West Main Line from London to Weymouth, and Poole railway station is less than one hundred metres from the southeastern corner of the bay. The A350 hugs the eastern shore and the A35 swings past its northern shore. In the northwest is Upton Country Park and Upton House, a public facility owned by the Borough of Poole. There is a marina on the western shore, south of the railway line.