Sete Cidades & Lagoa do Fogo Tours

The two lakes are one body of water. They meet at a narrow strait with a road bridge over it, and the water passes underneath. That single fact rules out the explanation most people reach for: there is no chemical difference between the blue lake and the green one.

What differs is depth and what is suspended in the water. Lagoa Verde is the shallower of the two, tucked against the wooded western wall, and it carries cyanobacteria all year round. Lagoa Azul is deeper and more open to the sky, and its phytoplankton comes and goes with the season. Depth and suspended material decide which wavelengths come back out, so the shallow lake under the trees returns green and the deep open one returns the colour of the sky above it. From Vista do Rei on a clear afternoon the line between them is sharp enough to look edited.

The legend is far better known than the optics, and it is worth telling as a legend. A princess with green eyes, a shepherd with blue ones, a king who forbade the whole thing, and two lakes made out of their crying. It is folklore, and one of the jeep operators on this page still sells the trip as a look at "the twin lake with the princesses and sheppards tears". There is nothing wrong with that, as long as nobody offers it to you as the reason for the colours.

Sete Cidades is, by the count in the published volcanological record, the most active volcano in the Azores: seventeen eruptions in the last five thousand years. The caldera you look into is the product of three separate collapses spread over twenty thousand years, and the smaller cones and maars scattered across its floor came afterwards. One of the buggy operators tells guests the volcano is thirty-six thousand years old, which is close enough to the first collapse to be fair.

Twelve products cover this area and the real choice is what you sit in, because the route barely changes. Everything goes up onto the rim, most things come down to the village, and the difference is whether you are driving, being driven, or pedalling.

The jeeps take the unpaved rim tracks that a hire car is not allowed on, and they are the highest-rated things here: the half-day at 48 EUR holds a 5.0 across 642 reviews. The quads and buggies go to the same places with more noise and more of your own effort, and they are the ones with a licence requirement. The small-group van is the comfortable version and includes lunch. The e-bike is the outlier and probably the best of them for anyone reasonably fit: it runs the rim and then drops into the caldera to the village, which is a descent nobody else offers.

Half the products here put Lagoa do Fogo in the afternoon, and it is worth knowing that you change volcano when you get back into the vehicle. Fogo is not part of Sete Cidades. It sits in the Água de Pau massif in the middle of the island, its inner caldera collapsed about fifteen thousand years ago, and its last eruption was in 1563.

The lake surface is at 575 metres and the rim above it reaches about 949. The water is three kilometres by two and a half and thirty metres deep. There is no road to the shore, no house on it, and nothing built inside the crater at all, because the basin has been a nature reserve since 18 June 1982. What every tour on this page gives you is the pull-off on the Serra da Barrosa road, on the flank of Pico da Barrosa at around 947 metres, looking down onto it.

Getting to the water is a walk, it is in none of these products, and it is a real descent and a real climb back out. The footwear people arrive in is the reason most of them turn round.

Vista do Rei is the one on the postcards, on the southern rim at about 650 metres, with both lakes below it and the shell of the abandoned Monte Palace hotel beside it. It is also where the coaches stop, and the railing is the reason people leave disappointed.

Boca do Inferno is the better photograph and it costs you a walk. One operator states twenty minutes each way on a path and says plainly that it is not suitable for guests with limited mobility. It looks along the caldera instead of across it and takes in Lagoa de Santiago as well as the twin lakes.

Miradouro da Lagoa de Santiago and Lagoa do Canário are the quiet ones, and several operators stop at them precisely because Vista do Rei is full. Down on the floor, the village of Sete Cidades has a church, a café and the bridge over the strait. Standing on that bridge is the cheapest possible way to understand that the two lakes are one lake.

One more thing appears in two of the jeep itineraries and gets no explanation from anybody: the Muro das Nove Janelas, a stone wall on the rim pierced by nine arched openings.

Four things about this area that change what you get, and none of them are in the price.

The 140 EUR quad is priced per vehicle, not per person. It seats two. Set against the 79 EUR single quad it is the cheaper option for a couple, and it looks like the most expensive thing on the page.

You need a driving licence valid in Portugal to drive anything with an engine. Two operators state it in their own text and say they check it before departure. Riding as a passenger is possible; a discount for doing so is not.

The 46 EUR product is a cruise excursion. It is timed to the ship and part of its morning goes to a pineapple plantation. If you are not on a ship, the 48 EUR jeep is a longer day in the caldera for two euros more.

Nobody refunds a cloudy viewpoint. What the better operators do instead is reverse the running order and put Sete Cidades in the afternoon when the morning is closed in. The small-group products are the ones with the flexibility to do it; a van of thirty on a fixed circuit is not.