Tubos
A submerged concrete structure with two large tubes off Cascais, Portugal, with a minimum depth of 26 m and no confirmed maximum: the area's one technical, experienced-only named dive site.
Last updated September 2026
The dive
Tubos is built around one feature: a submerged concrete structure with two large tubes, about a mile (1.6 km) southwest of the Laboratorio Maritimo da Guia, a real University of Lisbon marine research station on the Cascais coast. The dive starts at a minimum of 26 metres; how much deeper it runs is unconfirmed, so plan around that floor rather than a fixed depth band. Gorgonians in several colours cover the concrete and the tubes, with a large conger eel worked into the structure and octopuses reported in numbers around it; schools of a small schooling fish the operator calls pout move past as well, though nobody has confirmed that identification to species level. The route into or around the structure is not described anywhere, so a first-time visit here leans on your guide's local knowledge; no dive-by-dive account exists to follow instead.
What makes it special
Tubos is the area's one technical, experienced-only named site, built on an artificial structure where most of its named siblings sit on natural reef or in a sheltered bay, with a minimum depth of 26 m and no stated maximum. Pedra da Nau, a short boat ride away, stays shallow throughout for exactly the divers this site turns away; Pedra da Pata Roxa, Cascais' other advanced-only site, earns its reputation from a resident catshark on a natural sand-rock border, not from a man-made structure. What holds Tubos together is the combination the operator itself leans on: depth plus the tubes themselves, a landmark the other named sites reviewed alongside it do not share. That combination comes from a single operator's own description, with no independent trip report or review to corroborate it, so hold these specifics as provisional until a second account confirms them.
Know before you go
Access is by boat only, from Cascais marina or Estoril; boat trips on this stretch of coast typically run 15-30 minutes. No marine reserve, permit or diver fee applies here, and whether the site itself sits inside the Sintra-Cascais Natural Park's boundary remains unresolved. The area's usual 5-7mm semi-dry recommendation has not been verified at 26 m and beyond, so ask your operator what they actually run at this depth. Current strength has not been documented for Tubos or the wider area, so ask your operator for a same-day read before you descend. No maximum depth is confirmed for this site, so plan the dive as an open-ended deep profile and agree a target depth and gas plan with your guide before you descend.
Why Dive Tubos
What makes this dive site stand out.
- Concrete structure, two large tubes
Man-made structure about a mile southwest of the Laboratorio Maritimo da Guia, not a natural reef
- Minimum depth 26 m
No maximum depth confirmed by any source consulted
- Gorgonian-colonised structure
Gorgonians in several colours reported over the structure, with conger eel and octopus
- Boat-only, no shore option
Reached by RIB from Cascais marina or Estoril, roughly 15-30 minutes for this coast's named sites
Depth & Profile
Conditions & difficulty
No required certification level is named for this site specifically; the operator frames it only as 'a dive only for experienced divers.' Given the 26 m starting depth and unconfirmed maximum, Advanced Open Water here reflects a cautious floor this page sets, since no source states an actual minimum for the site.
Summary
Based on the operator's own 'experienced divers only' framing and a minimum depth close to the working Advanced Open Water ceiling.
Safety considerations
What can go wrong here, and what divers do about it. Conditions change - take the briefing from the operator on the day.
- Depth: Minimum depth 26 m with no stated maximum, explicitly framed by the operator as a dive only for experienced divers.Plan for a deep-dive profile and confirm the day's target depth and gas plan with your guide before descending.
- Current: Current strength is undocumented for Tubos itself and for the wider Cascais/Estoril area, on a boat dive to an offshore structure below 26 m.Ask your operator for a same-day current read before descending, since no source documents typical current strength here.
Marine Life
Rules and permits
Frequently Asked Questions
How deep is Tubos, and what certification do I need?▾
The minimum depth is 26 m; no maximum is stated. No operator names a required certification for this site specifically, but the operator itself calls it a dive only for experienced divers. Advanced Open Water is the practical floor here; no source sets it as an actual minimum, and the true maximum could run deeper than the AOW ceiling, so confirm the planned depth with your guide before booking.
Is Tubos the same site as 'Emissario'?▾
Not established either way. Emissario is a separately reported wastewater outfall pipe said to extend 3 km south of the coast, from a single account with no depth or difficulty detail. Nothing ties the two leads to a shared reference point to compare positions, so this stays an open question, neither confirmed as a match nor ruled out.
Does more than one dive centre run trips to Tubos?▾
One local operator is confirmed for this site. A dive-site catalogue page also credits a second centre based in Portimao, roughly 280 km south in the Algarve, as catering to it, which is geographically implausible for a Cascais boat dive and is not corroborated anywhere else. That second credit stays an unresolved catalogue listing unless an independent source confirms it as an actual second operator.
Is Tubos inside a marine reserve, or does it need a permit?▾
No marine reserve, permit, quota or fee regime applies to this site or the wider Cascais/Estoril coast. Whether Tubos itself, a mile offshore, falls inside the Sintra-Cascais Natural Park's boundary remains unresolved; the park is a coastal landscape designation in any case, not a marine diving permit regime.
Where exactly is Tubos, and what are its coordinates?▾
No verified coordinates exist for this site. It is described as sitting about a mile (1.6 km) southwest of the Laboratorio Maritimo da Guia, a University of Lisbon marine research station in Cascais; use that landmark to navigate, not a GPS fix.
What will I see at Tubos?▾
A gorgonian 'forest' in several colours over the concrete structure and its two tubes, a large conger eel, and octopuses, per the one operator account describing the site in detail. Schools of a small schooling fish the operator calls pout also turn up, though that identification has not been confirmed to species level.
What is the concrete structure at Tubos, and why was it built?▾
Not established. What the structure and its two tubes originally were, whether a discharge or outfall pipe, a former hydrographic installation, or something else, is unknown, so treat any specific explanation offered as speculation until a source confirms one.
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