Tres Marias
Also known as: 3 Marias, 3 Marias Machico, Rocha 3 Marias, Três Marias
Three volcanic seamounts east of Machico bay, Madeira, rising from a 20m base toward the surface, with a tunnel of rare tree coral and hunting amberjack.
Last updated September 2026
The dive
Three separate volcanic pyramids rise from a base near 20 metres east of Machico bay, with an average depth across the group closer to 10 metres. A short tunnel opens through one of the three, holding a rare tree coral, Dendrophyllia ramea, along its walls. The richest exploring concentrates at the last of the three pyramids, where overhangs and gaps give divers several distinct places to work through on a single dive. Amberjack hunt around the rock often enough to be one of the site's regular sightings, and morays share the same ledges as the coral.
What makes it special
Three separate volcanic pyramids share this one site, a shape none of its Machico-cluster neighbours match: elsewhere along this stretch the rock stays one wall or one cone, never three distinct peaks together. Dendrophyllia ramea colonises a tunnel through one of the pyramids, an orange coral uncommon enough on this coast that it stands out as the site's own signature.
Know before you go
Treat the tunnel like any swim-through: check it is clear and keep the exit in view before you commit to it. The coral is slow-growing and easily damaged by contact, so keep fins and gauges clear of the rock walls it grows from.
Why Dive Tres Marias
What makes this dive site stand out.
- Three volcanic pyramids
Rise from a base near 20m; one source describes the peaks breaking the surface
- Tree coral tunnel
A small tunnel holds rare Dendrophyllia ramea tree coral
- Hunting amberjack
Large amberjack are frequently seen hunting around the pyramids
Depth & Profile
Conditions & difficulty
Neither operator source states a minimum certification. The site's 20m base exceeds the 18m Open Water ceiling, so the deeper stretch is treated as Advanced Open Water.
Summary
Easier on the shallower stretches near the pyramid tops; the 20m base is more demanding. This offshore cluster likely sees more current than Madeira's sheltered south coast, though no operator source rates the current directly.
Safety considerations
What can go wrong here, and what divers do about it. Conditions change - take the briefing from the operator on the day.
- Overhead: A short tunnel cuts through one of the pyramids. Neither source describes it as requiring specialty training or penetration, but it is still a brief overhead passage.Check the tunnel is clear and keep the exit in sight before committing to it.
Marine Life
Rules and permits
- Conduct: no touching, no taking anything, no disturbing wildlife.
Diving with scuba or a scooter to watch marine mammals or turtles is prohibited, unless for authorised science or filming; a chance meeting is not.
Frequently Asked Questions
Is this Tres Marias the same dive site as the one in Mexico?▾
No. A separate, unrelated dive site with the same name lies off San Carlos, Sonora, in Mexico. This Tres Marias is the Madeira seamount cluster east of Machico bay, and the two share nothing but a name.
Why doesn't either operator source state a minimum certification for Tres Marias, even though it reaches 20 metres?▾
Neither of the two operator sources found for this site names a required certification. Graded to the standard Open Water to Advanced depth ladder, the 10-metre average sits within Open Water limits, but the 20-metre base of the pyramids exceeds the 18-metre Open Water ceiling, so treat the full route as an Advanced Open Water dive until your guide briefs you otherwise.
Do the Tres Marias pyramids really break the surface?▾
One of the two operator sources naming this site describes the peaks rising clear of the water; the other gives only the depth range and says nothing about an above-water point. The figures that are independently corroborated between the two, an average depth near 10 metres and a maximum of 20, name no emergent peak, so this page plans the dive on that better-supported range rather than the single surface-breaking description.
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