It's large, fan-like fins wave and flare like the skirts of a Flamenco dancer, revealing vibrant shades of rust and orange with flashes of royal blue as it hunts its prey under the cover of night. As beautiful as its dance may be, one prick from one of its long dorsal spines will inflict a very painful burning sensation.

Renowned diving physiologist Dr Neal W Pollock filmed a EUROTEK TEKTalk where he discussed the foundations of decompression physiology, M Values and what Gradient Factors are.

Pollock is the Research Director at Divers Alert Network (DAN) and a Research Associate at the Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center. Both positions are based in Durham, North Carolina.

Sweden's military has now analyzed the video footage provided by Swedish wreckhunter group Ocean X Team and concluded that it is the wreck of a Russian submarine that sank after a collision with a Swedish vessel in 1916 during the First World War. Ocean X was the team who also found the "Baltic anomali"

Artefacts on the wreck indicate it might date to the American Revolution. Amid the shipwreck’s broken remains are an iron chain, a pile of wooden ship timbers, red bricks (possibly from the ship cook’s hearth), glass bottles, an unglazed pottery jug, a metal compass, and another navigational instrument that might be an octant or sextant.