Sao Martinho do Porto: The Shell-Shaped Bay

São Martinho do Porto has one of the most unusual beaches in Portugal: an almost perfectly round, shell-shaped bay sheltered from the Atlantic, with calm, shallow water. That makes it a favourite for families on the Silver Coast. Here’s what to know.

Quick answer: São Martinho is about 1 hour 15 minutes north of Lisbon, 15 minutes from Nazaré. Swim in the calm bay, walk the promenade, and climb to the viewpoint on the hill above the entrance to the bay. It’s ideal for young children, and a quieter base for exploring Óbidos, Nazaré and Alcobaça. See places to stay in São Martinho.

Why go

Almost every beach on Portugal’s west coast faces the open Atlantic, with big waves and strong currents. São Martinho is different. The sea comes in through a gap in the cliffs only a few metres wide, and inside it forms a round bay with fine sand and gentle water. Children can paddle safely, and you can actually swim without fighting the surf. The town itself is small and low-key, a seaside resort since the late 19th century, and it feels very Portuguese, especially outside August.

Its history goes back much further. The bay is first mentioned in 1257, and for centuries it served as the port of the monks of Alcobaça, with fishing boats and shipyards that built vessels in the Age of Discovery. The bay was much larger then and has slowly silted up.

Things to do

The bay

The beach curves all the way round the bay. The water near the town is shallow and calm, ideal for paddling and swimming. It’s still the Atlantic, so expect it to be cool, even in summer. The far side of the bay, towards Salir do Porto, is quieter.

The tunnel to the ocean

Near the harbour end of the bay, a short pedestrian tunnel, about 60 metres long, cuts through the rock to the open sea. Walk through and you see the contrast straight away: still water behind you, crashing waves in front. It takes a few minutes and is a favourite with children. Stay back from the rocks on the ocean side, where waves can wash over without warning.

Santo António viewpoint

Walk up the hill at the mouth of the bay, where there is a small lighthouse. From the top you see the full shell shape of the bay on one side and the open ocean on the other. Allow 30 to 45 minutes there and back. It’s best in the late afternoon.

The promenade

The tree-lined seafront has cafés, ice cream shops and seafood restaurants. In the evening it’s the place for a stroll.

Salir do Porto dune

Across the bay, the village of Salir do Porto sits below a huge sand dune, around 50 metres high and often described as the largest in Portugal. You can walk round the bay to it or drive there in a few minutes. A wooden boardwalk of about 3 km there and back runs from the Salir do Porto car park through the dunes and past the mouth of the Tornada river. It is flat and easy for small children. Climbing the dune itself is hard work in soft sand, but the view is worth it.

Water sports

On calm days the bay is good for paddleboarding and kayaking. Rental is usually available on the beach in summer.

How long to spend

A half-day visit covers the tunnel, the viewpoint and a swim. A full day lets you add a long lunch and a walk to Salir do Porto. Many people stay several nights and use it as a calm base for day trips.

Getting there

• By car: about 110 km from Lisbon on the A8, usually around 1 hour 15 minutes. Parking near the seafront fills up fast in summer, so arrive early.
• By bus: Rede Expressos runs direct buses from Lisbon’s Sete Rios terminal several times a day, and the direct ones take about 1.5 hours. Rodotejo’s Rápida Verde express buses also run from Campo Grande in Lisbon to Óbidos and Caldas da Rainha. Check current times before you go. See Portugal by bus.
• By train: the station is on CP’s Oeste line. Since storm Kristin on 28 January 2026 there have been no trains between Meleças (near Lisbon) and Caldas da Rainha, only replacement buses. Trains do run north of Caldas, and a few a day stop at São Martinho. Trains are due back between Torres Vedras and Caldas in late 2026 and as far as Meleças in early 2027. Until then, the express bus or a car is far easier.

Food

• Grilled fish: sardines in summer, plus sea bream and sea bass.
• Seafood rice: arroz de marisco is a classic here.
• Local sweets: try the cavacas from nearby Caldas da Rainha, or the convent sweets of Alcobaça.

When to go

June and September are ideal: warm enough for the beach without the crowds. July and especially August are very busy with Portuguese families, and the town’s summer festival, with free concerts, usually runs over several days in mid to late August. Out of season the town is quiet, and some restaurants close or cut their hours.

Nearby

• Nazaré: see Nazaré.
• Alcobaça: see the Alcobaça Monastery.
• Óbidos: see Óbidos.
• Foz do Arelho: see Foz do Arelho.
• Caldas da Rainha: a market and ceramics town about 20 minutes south. Note that treatments at its thermal hospital have been suspended since 20 August 2026. See Caldas da Rainha.

Tips

• Summer: busy with Portuguese families in August, so book early.
• Water: still the Atlantic, so cool, but much calmer than the open beaches.
• Train: the Oeste line has no trains south of Caldas da Rainha until the repairs are finished, so a car or the express bus is easier.
• Big waves: for the opposite experience, see the Nazaré big waves in winter.

FAQ

Is São Martinho do Porto good for children?

Yes. The sheltered bay has shallow, calm water near the town, which makes it one of the safest places for young children on Portugal’s west coast. Swim where lifeguards are on duty.

Can you visit São Martinho without a car?

Yes. Direct Rede Expressos buses from Lisbon take about 1.5 hours, and the beach, tunnel and viewpoint are all walkable from the centre.

Is São Martinho or Nazaré the better base?

São Martinho is quieter and better for swimming with children. Nazaré is livelier, with more restaurants and the big-wave lookout, and is only 15 minutes away.

More: the Silver Coast, Portugal with kids and the best hotels in Nazaré.

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