Travel guide · Islands
Los Gemelos and the lava tunnels: the other Santa Cruz, straight down and underground
Los Gemelos, the twin sinkholes of Santa Cruz, and the island's walkable lava tunnels: how to visit both in a highlands half-day, costs, the finches to…
Most visitors meet Santa Cruz at the dock in Puerto Ayora and the beach at Tortuga Bay and never go up. That is a mistake. The highlands hold the island’s two strangest sights, a pair of enormous pits swallowed into the forest and lava tunnels you can walk through for hundreds of metres, and they combine naturally with the giant tortoise reserves into one half-day. This page covers both: what they are, how the visit works, what it costs and what to look for while you are there.
Key facts
| Los Gemelos | The lava tunnels | |
|---|---|---|
| What | Two collapsed magma chambers (“the twins”) in the Scalesia forest beside the road to Baltra | Tubes left when the surface of a lava flow hardened and the molten rock drained out |
| Where | Highlands of Santa Cruz, just past Santa Rosa, 20 to 30 minutes by taxi from Puerto Ayora | On private ranches in the highlands (El Chato, Rancho Primicias and others) and near Bellavista |
| Cost | No fee; the site is on the main road | Included in the US$10 entry at El Chato; a few dollars at the other ranches |
| Time | 30 to 60 minutes for the viewpoints and the forest loop | 20 to 40 minutes per tunnel |
| Best for | Birders: eight of the thirteen Darwin’s finch species, vermilion flycatchers, short-eared owls | Geology, and anyone who likes walking inside a volcano’s plumbing |
Los Gemelos: the twin sinkholes
First, a correction to what you will hear around town: Los Gemelos are not craters and no eruption made them. They are sinkholes, formed when the ground collapsed into empty magma chambers below, which is why their walls are sheer and their floors are forest. The two pits sit on either side of the road through the highlands, each several hundred metres across and well over a hundred metres deep, and the road passes within a few steps of the rim.
The visit:
- Short paths lead to viewpoints over both pits, and a loop trail of about 500 metres circles the larger one through the forest: an easy hour if you take it slowly.
- The forest is Scalesia, the tree daisy that exists only in Galápagos, draped in moss and in the garúa mist for much of the cool season. The vegetation inside the sinkholes is lusher than on the road above because moisture collects below.
- Birding is the real draw. Eight of the thirteen Darwin’s finch species have been recorded here, including the woodpecker finch, the one that uses a cactus spine as a tool, and the vermilion flycatcher flashes red in the branches. Short-eared owls sometimes hunt along the rim.
- The site sits inside the national park and is visited with a guide on tours; taxi drivers from Puerto Ayora stop here as a matter of course, and the trail is signposted.
The lava tunnels
A short drive away, the lava tunnels show the third dimension of the island’s geology. When the surface of a lava flow cooled and hardened while the molten rock kept running underneath, the river of lava eventually drained away and left a tube. Some run only a few metres; the longest on Santa Cruz runs for more than a kilometre. The ones open to visitors are large enough to stand in for most of their length, lit in places, and reached by a stairway or a ladder.
Three practical notes from people who have been in:
- Bring a flashlight or use your phone even on the lit sections; the lighting is not continuous.
- The floor is wet and uneven, so closed shoes are not optional.
- One or two tunnels have a low section where you crawl for a few metres. Guides say so beforehand, and there is always the option of turning round.
Guides point out the lava “drips” on the ceiling, the flow marks on the walls and the roots of the forest above pushing through the roof. The tunnels sit on the same ranches as the giant tortoises, which is why the standard highlands tour visits both in one stop. The tortoise side is in our El Chato guide.
Putting the half-day together
The standard highlands tour from Puerto Ayora runs: tortoise reserve (El Chato or Rancho Primicias) first, then a lava tunnel, then Los Gemelos on the way back, and lunch in town or at a highlands ranch. Three ways to do it:
| How | Cost | Notes | |
|---|---|---|---|
| Taxi with the driver waiting | Agree the circuit at the pier taxi rank | A few tens of dollars for the half-day, split among up to four passengers (check current rates) | The simplest; drivers know the loop |
| Guided highlands tour | Booked in town or through us | US$20–80 per person depending on group size and whether lunch is included | Adds the naturalist’s explanations, which the sinkholes and tunnels deserve |
| Bicycle | Rent in town | Bike hire only | A real climb up, a long freewheel down; for fit riders who do not mind the traffic |
Two notes for planners. First, the highlands are cool, damp and often muddy, so bring a light rain layer and shoes with grip whatever the forecast says in town. Second, Los Gemelos sits on the airport road, so tour groups pass through all day; early morning and late afternoon are quieter.
How cruises include it
Nearly every cruise spends part of a day in the Santa Cruz highlands, usually combined with the Charles Darwin Research Station: 1,216 of the departures in our live schedule include the highlands, and 505 on 9 yachts list Los Gemelos by name. Cruise visits are short, an hour or so at the tortoises and a stop at the pits, which is why land-based travellers with a free day in Puerto Ayora get more out of the highlands than cruise passengers do.
Why geology readers should not skip it
Santa Cruz is a dormant shield volcano, and Los Gemelos plus the tunnels are the clearest lesson in how these islands are built that you can get on foot: the sinkholes show the island’s plumbing from above, the tunnels show it from inside, and the fresh lava flows elsewhere (Sullivan Bay on Santiago is the extreme) show the raw material. If that sounds like your kind of day, our hiking guide lists the highlands walks, and getting your bearings places Santa Cruz in the archipelago.
Frequently asked questions
Are Los Gemelos craters?
No. They are sinkholes: the ground collapsed into empty magma chambers below. There was no eruption at the surface, which is why the walls are sheer and the floors are forested.
How much does it cost to visit Los Gemelos?
Nothing. The site is beside the main road through the highlands and has no entry fee. You pay for the taxi or the tour that takes you there.
Can you walk inside the lava tunnels on Santa Cruz?
Yes. Several tunnels on the highland ranches are open to visitors, lit in places and tall enough to stand in. The tunnel at El Chato is included in the reserve’s US$10 entry; others charge a few dollars.
How do I get to Los Gemelos from Puerto Ayora?
By taxi (20 to 30 minutes along the road to Baltra), on a guided highlands tour, or by bicycle for fit riders. Most people combine it with a tortoise reserve and a lava tunnel in a half-day.
Which finches can I see at Los Gemelos?
Eight of the thirteen Darwin’s finch species have been recorded in the Scalesia forest here, including the woodpecker finch, along with the vermilion flycatcher and, with luck, a short-eared owl.
Related reading
The tortoises on the same ranches are in the El Chato guide; the island as a whole, from the airport to the beaches, is in the Santa Cruz guide; and the species to tell apart in the forest are in Darwin’s finches.
Sources
Last verified: October 2026