São Martinho do Porto

São Martinho do Porto occupies a bay that the sea reaches through a gap in the cliffs only a couple of hundred metres wide, so the water inside is almost enclosed - flat, shallow, warm by Portuguese Atlantic standards and safe for children, which is a rare combination on a coast that is otherwise surf and rip currents. The shape from above is a near-perfect shell, best seen from the clifftop viewpoint on the northern arm, reached by a path from the town. It was a working port until the bay silted, and the town that remains is a modest resort with a promenade, a bandstand and family hotels, busy in August and quiet otherwise. Outside the gap the ocean behaves normally, and Nazaré with its enormous winter waves is twelve kilometres north, which is a useful illustration of what the bay is protecting against.

What you actually see

• The enclosed bay - a shell shape open to the sea through a narrow gap.
• The calm water - flat and shallow, unusual on this coast.
• The clifftop viewpoint - the northern arm path giving the whole shape.
• The old port - a working harbour until silting closed it.

When to go

June to September for swimming. Half a day, or two if using it as a base. August is crowded with Portuguese families.

Honest expectations

The bay is shallow and at low tide much of it is exposed mudflat and sand. Water quality varies with the tide flushing. The town is a modest family resort with little else to do. Parking is hard in August.

Nearby

Nazaré and its big-wave canyon are north; Alcobaça and its monastery are inland.