Benagil cave boat tour: every boat, what it costs, and which ones go inside

Every listing on this coast uses the same three words — Benagil, caves, tour — and they describe two completely different mornings. The difference is the size of the hull.

The entrance to Algar de Benagil is a gap in the cliff wide enough for a small craft and not much more. The harbour master allows three motorised boats under twelve metres inside at the same time, or a single larger boat on its own. In practice that means the RIBs and speedboats go in and turn, and the eighty-seat catamarans work the coast outside.

Neither is wrong. The catamaran is a genuinely good two and a half hours: flat deck, shade, a swim stop in clear water, and the cliffs from Albufeira to Benagil at a speed that lets you look at them. The speedboat is a different sport — faster, wetter, into every gap in the rock, and inside the cave for the two minutes it is allowed.

What goes wrong is booking one while expecting the other. That is the single most common complaint on this coast, and it is entirely avoidable.

Check-in. Names against a list on the pontoon, wristbands, life jackets. Most operators want you fifteen to thirty minutes early, and the marina car parks in Portimão, Albufeira and Lagos are paid.

The run out. Once past the harbour wall the engine opens up. On a speedboat this is the wet part and the fun part; on a catamaran it is the part where people find a seat and put sunscreen on.

The caves before the cave. The limestone starts long before Benagil. Stacks standing offshore, arches you can drive through, tunnels that go in twenty metres and stop. Most are unnamed and most skippers slow down at the good ones.

Algar de Benagil. The chamber, the sand, the round hole in the roof. Two minutes if you are on a motorised boat, and the skipper will be counting — the fines for overstaying run from €300 upward, so nobody is generous with it.

The swim stop. Usually off Praia da Marinha, in water clear enough to see the anchor. Ten minutes on most trips, longer on the half-day cruises.

Back. Slower, sun higher, the same rock a different colour.

If you want to be under the opening long enough to look at it rather than photograph it, no motorised boat will do that. Two minutes is two minutes, and in July you may spend longer waiting outside for a slot than you spend inside.

If you get seasick, take the widest hull on the shortest crossing and accept that you are seeing the cave from outside. A catamaran out of Albufeira is the steadiest thing on this coast.

And if the sea is running, the small boats are the first to be pulled. That is not the operator being cautious for the sake of it — the entrance faces the swell.

Benagil gets the photographs, but it is one gap in about fifteen kilometres of limestone that has been worked by the Atlantic for a very long time, and the rest of it is why a two-hour trip does not feel padded.

West of the cave. Carvoeiro sits on a small cove with houses stacked up the slope, and beyond it the cliffs run out to Algar Seco, a shelf of eroded rock full of holes and blowholes. Boats out of Portimão and Lagos pass Ferragudo and the old fort at the mouth of the Arade on the way east.

East of the cave. Praia da Marinha is fifteen minutes away and is the beach most trips anchor off: two rock arches standing in the water, and a cove that turns pale green when the sun is high. Past that, Albandeira has its own arch and Praia da Corredoura is the one people photograph from the clifftop path without knowing its name.

Between them. Dozens of unnamed grottoes. Some are wide enough to enter, some stop after ten metres, and a few go through the headland and come out the other side. This is where a small boat earns its money: it can take you into things a catamaran can only point at from a hundred metres offshore.

Take the speedboat from Lagos at $37 or the one from Albufeira at $34. They are within a few dollars of the cheapest ticket on the coast, they are small enough to go through the arch, and the two hours are spent moving rather than sitting. The Albufeira one adds dolphin watching and has more reviews than anything else here; the Lagos one covers the most varied stretch of cliff.

Take the catamaran at $33 instead if the group includes anyone who would not enjoy a small boat at speed, or if the swim stop matters more than the cave.

Take the cruise with lunch at $50 if you want the morning to be the day rather than a slot in it.

And if there are four or six of you, price the private boat before dismissing it. At $516 for the hull it is not far off six catamaran seats, and you set the timing.