Category Archives: Technical Diving

Technical diving is scuba diving beyond the limits of recreational diving in terms of depth deeper and longer, breathing mixed gases and execute decompression diving. Overhead environment, CCR Rebreather diving, DPV… are part of technical diving.

Playing with the Halocline

A cave dive playing in the halocline, meeting with remipedes

This cave is just amazing, dark with a very well defined halocline. Recommended to dive with Nitrox and with stage side mount or stage back mount configuration as it is fairly deep and you will want to stay as long as posible.

Halocline: from Greek hals, halo- ‘salt’ and klinein ‘to slope’

The halocline is the area within a body of water that marks a drastic change in salinity.

Haloclines are common in underwater caves near the ocean. The fresh water, less dense, forms a layer above the salt water from the ocean. For cave divers, it causes the optical illusion of air space in caverns. Passing through stirs up the layers and blurs the vision.

The halocline itself is responsible for the formation of the cave systems. The mixing of the saltwater and freshwater results in reactive brackish water that dissolves the limestone, eroding the rock and enlarging a cave’s passageways.

Because different water densities meet at the halocline and both organic and inorganic particulates accumulate there, it is chemically speaking an intriguing place.


Contact us for private guided dive in hidden side passages.


Pozo Azul Exploration Project

Pozo Azul exploration: A fascinating cave exploration project!

Pozo Azul is currently the longest cave dive penetration in the world,
And more than 9.4km of diving accumulated over 5 sumps are required to reach the furthest point from the single entrance.

Located in the village of Covanera, Burgos, Spain, El Pozo Azul is probably one of the most challenging cave exploration project. Already 5 sumps (maximum depth 71m) had been explored. And in 2015 J. Mallinson pushed the exploration solo and discovered a 6th sump and spent a total of 60 hours inside the cave.

In 2001, Jason Mallinson first visited the site with Rupert Skorupka. At that time the known part of the cave was a 1st 700 m sump, then a dry tunnel of 300 metres, followed by a second sump penetrated for 780 m. On that same trip the sump was pushed to 1250 m.

Jason then returned year after year, sometimes with other top divers, and sometimes on his own.

In 2009 the sump was passed after 5160 m – the longest sump to be passed in the world, to reach Sump 3. This was passed in 2011 and proved to be over 3 km long. From this point, the sumps became shorter and the amount of dry passage longer.

Sumps 2 and 3 are actively linked and are in fact one long sump of more than 8km in length.

in 2015 Jason returned solo. He traversed more than 10 km of sump to explore dry passage and find a sixth sump.
Pozo Azul - Survey map
Pozo Azul – Survey map