Terceira Island: Underground Caves, Sulfur Springs & Biscoitos Pools

Summary

Terceira’s caves, volcanic springs and wild swimming spots

You’ll wander Terceira’s forests with ducks underfoot, walk through ancient lava tunnels with a local guide, feel volcanic heat at Sulfur Furnas, and dip into wild Atlantic pools at Biscoitos. Expect earthy smells, honest laughter, and moments that linger long after you’ve left.

What’s the experience like?

“Don’t step on the duck,” our guide Nuno grinned as we shuffled out of the van at Lagoa das Patas. The ground was still damp from last night’s rain — you could smell wet earth and leaves, and honestly I almost did step on a duck (they’re everywhere). There were families picnicking under crooked trees, kids chasing birds. We wandered along the stream that comes down from Serra de Santa Bárbara, and for a minute it felt like time slowed down — just water moving, birds calling, Nuno pointing out some plant I’d never heard of (I forgot the name already).

The next stop was Gruta do Natal. I thought “lava tunnel” sounded dramatic but inside it’s actually kind of peaceful — cool air on your skin, your footsteps echoing. Nuno handed us helmets (“fashionable,” he joked) before we ducked into the dark. My shoes crunched on old volcanic rock. You can see where molten stone carved out these weird shapes — like someone took a hot spoon to the earth. Outside again, Lagoa do Negro looked almost black under heavy clouds; I tried to take a photo but it didn’t catch how quiet it felt there.

At Furnas do Enxofre you get this sharp smell — sulfur in your nose, not exactly pleasant but sort of exciting? Steam hissed up from cracks in the ground while we walked the little trail. It made me think about how alive this place is underneath everything. Nuno told us stories about eruptions and old beliefs; I got distracted by a dog barking somewhere off in the mist.

The last bit was Biscoitos’ natural pools. Black volcanic rocks sliced into clear blue water — locals were already swimming even though I thought it was freezing (maybe I’m just soft). The Atlantic crashes right up against you if you stand close enough. I sat on a warm rock for a while with my feet dangling in; salt spray on my face, sun finally coming out. Didn’t want to leave yet — isn’t that always how it goes?

Step-by-step itinerary

Day 1 — Explore Terceira's natural caves and pools

• Visit Lagoa das Patas leisure area
• Walk through Gruta Natal lava tunnels
• See Lagoa do Negro up close
• Observe sulfur smoke at Furnas do Enxofre
• Stop at natural pools of the Biscoitos

Top questions

How long does this Terceira underground van tour last?

This is a half-day tour covering several stops around Terceira Island.

Are hotel pickups included in this tour?

Yes, pickup and drop-off are included for your convenience.

Is Algar do Carvão cave included right now?

No, Algar do Carvão is temporarily closed for reconstruction; instead you’ll visit Biscoitos natural pools.

What should I bring for the lava cave section?

Wear comfortable shoes suitable for walking on uneven surfaces; helmets are provided by your guide.

Is lunch included in this tour?

No lunch is included; plan to eat before or after the tour.

Are there any health restrictions?

This tour isn’t recommended for pregnant travelers or those with spinal or cardiovascular issues.

Can anyone swim at Biscoitos natural pools?

The pools are open to all visitors but be aware of weather conditions and cold water temperatures.

What’s included

Your day includes pickup and drop-off by air-conditioned vehicle, guidance from a knowledgeable local guide throughout each stop, entry to Gruta do Natal cave with safety equipment provided, plus personal accident insurance so you can relax and enjoy every moment along Terceira’s wild routes.