Foz do Douro, formerly a fishermen’s quarter but a distinctly more upmarket beach suburb these days, is literally the “end of the Douro”, around 5km from the city centre. It’s on several bus routes, including the #500 from São Bento (and the #78, on from the Serralves museum and park), but it’s a nice idea to take the tram along the river at least one way – catch #1 (from Ribeira) or #18 (Igrjeja do Carmo) down to the terminus at Massarelos and change there on to the #/1 which stops by the riverside gardens in Foz.
The confluence of river and ocean is dominated by the squat Forte São João Baptista, still a military base, beyond which stretch several kilometres of coves and beaches, backed by the cafés and bars of Avenida do Brasil, which becomes the hub of Porto’s summer nightlife. At the northern end stands the Castelo do Queijo, so-named (Cheese Castle) because it was built upon boulders that apparently looked like cheese.
From here, Avenida da Boavista (and the #502 bus) runs straight back into the city. The water at Foz isn’t the cleanest – being downstream from Matosinhos port and its refinery – but the beaches are fine, sheltered bathing areas are marked out and children can paddle in the rock pools.