Boca das Caldeirinhas
Also known as: Boca da Caldeirinha, Caldeirinhas
A volcanic-crater wall dive on Faial's Horta bay, with a black-coral cave and dense fish life along the border of a Category Ia marine reserve.
Last updated September 2026
The dive
The wall starts where the twin volcanic crater meets open water, on the site's sea-facing exterior border, with the crater's own flooded basin sealed off just behind it. A shallow shelf between about six and ten metres holds moray eels, ornate wrasse and parrotfish grazing the rock, then the ground drops into a vertical wall that carries a resident grouper and, around thirty metres, a small cave holding a branch of black coral, the dive's signature feature. The wall keeps descending past that point, reported as deep as forty to fifty metres for divers equipped to follow it. One diver's own log from a September 2021 dive recorded 28 metres over 47 minutes at 22°C, within this range.
What makes it special
Boca das Caldeirinhas is named for, and dived right alongside, the only marine protected area in the Azores carrying the strictest IUCN classification: Reserva Natural das Caldeirinhas, a ten-hectare reserve of twin flooded craters whose interior access is forbidden by government decree1. The dive works the crater's outer, sea-facing wall only; with the interior closed, life concentrates along this exterior border where the diving happens. Black coral (Antipathella wollastoni) fills a small cave partway down the wall, and moray eels, ornate wrasse, parrotfish and a resident grouper work the rock above and below it.
Know before you go
Staying on the seaward side of the wall matters for more than the view: the crater basin behind it, the Reserva Natural das Caldeirinhas, is strictly off-limits to divers. The black-coral cave on the wall is a brief overhead pause, not a passage to swim through; treat it as a look-in and keep the exit in sight. Certification needs split by source: the official Azores dive directory opens the shallow shelf to all divers and reserves the wall and cave below for a separate technical-diving route; one operator instead rates the whole dive Advanced, with no shallow option named. Treat the shelf as an Open Water depth and the wall below about thirty metres as Advanced-or-deeper, whichever operator you book with.
Why Dive Boca das Caldeirinhas
What makes this dive site stand out.
- Black-coral cave
A resident branch of black coral fills a small cave partway down the wall
- Forbidden-reserve border
Dives the sea-facing edge of an IUCN Category Ia marine reserve
- Shelf-to-wall profile
A shallow shelf gives way to a wall that keeps descending
- Grouper and moray wall
A resident grouper and two moray species work the rock above and below the cave
Depth & Profile
Location
38.5159°N, 28.6294°W
Conditions & difficulty
The shallow shelf suits Open Water divers. The wall below about thirty metres and the black-coral cave are graded to a separate technical-diving circuit by the official Azores dive directory; the site's own dive centre instead rates the whole dive Advanced, with no shallow-only option named
Summary
Easy on the shallow shelf; advanced to technical on the wall and in the black-coral cave below
Safety considerations
What can go wrong here, and what divers do about it. Conditions change - take the briefing from the operator on the day.
- Conditions: The crater interior, the Reserva Natural das Caldeirinhas, is the only Category Ia marine reserve in the Azores; the dive works its sea-facing exterior border onlyStay on the seaward side of the wall with the guide; do not cross into the crater basin
- Overhead: A small cave on the wall around 30m holds the black-coral branch; no operator documents its full dimensionsTreat it as a look-in, not a penetration, and keep the exit in sight
Marine Life
Rules and permits
Frequently Asked Questions
Do I need Advanced Open Water to dive the whole of Boca das Caldeirinhas?▾
It depends which route you book. The official Azores dive directory frames the site in two tiers: a shallow shelf open to any diver, and a separate technical-diving circuit down the wall and into the black-coral cave, reported at 18 metres average and up to 50 metres maximum. The site's own dive centre instead rates the entire dive Advanced, with a plateau at six metres stepping down through the wall to around 40 metres and no shallow-only option offered. In practice: the shelf is an Open Water depth, and anything past about thirty metres on the wall needs Advanced training or deeper, whichever centre you book with.
Is DiveAzores the only dive centre that runs this exact site?▾
DiveAzores, based in Horta, is the one dive centre confirmed to run Boca das Caldeirinhas directly. Norberto Diver, Faial's dominant operator, dives generally around the Monte da Guia protected area but does not name this site specifically on its own pages.
References
- 1.Governo dos Açores / Parques Naturais dos Açores — Caldeirinhas Natural Reserve
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