A backrest for scuba diving comprising a support element, a first strap strapping the support element to the diver's body and a second strap strapping an air cylinder to the support element. The support element has first slots passing the first strap and second slots passing the second strap. The first slots delimit a right portion and respectively a left portion of the first strap, independently adjustable over the right shoulder and right side and respectively over the left shoulder and left side of the diver. The support element comprises a support plate, a right angular profile having a first and second right wing, a right bracket supported by the first right wing, a left angular profile having a first and second left wing, a left bracket supported by the first left wing.

Combining several capillary tubes in one depth gauge, which measure the depth in different ranges, will allow obtaining a measuring scale close to linear and eliminate the main disadvantage of a capillary depth gauge.

Methods and devices including implantable micro-sensors used to detect tissue-dissolved inert gas and to detect microbubble formation to avoid Caisson disease are described. The disclosed methods and devices are based on measuring the refractive index changes in hydrophobic liquids after absorbing an inert gas such as nitrogen. The changes in the refractive index are based on implementing one of an interferometry, optical microcavity resonance shift, a photonic crystal resonance, a beam deflection, a resonance tuning or detuning, an amplitude change, or an intensity change method.

Methods and devices including implantable micro-sensors used to detect tissue-dissolved inert gas and to detect microbubble formation to avoid Caisson disease are described. The disclosed methods and devices are based on measuring the refractive index changes in hydrophobic liquids after absorbing an inert gas such as nitrogen. The changes in the refractive index are based on implementing one of an interferometry, optical microcavity resonance shift, a photonic crystal resonance, a beam deflection, a resonance tuning or detuning, an amplitude change, or an intensity change method.

An underwater propulsion device is disclosed comprising two sleeves for fitting around each of a user's lower legs, with each sleeve mounting a propulsion unit, and the sleeves being connectable by a bar between them during underwater operation of the device by the user.

An underwater propulsion device is disclosed comprising two sleeves for fitting around each of a user's lower legs, with each sleeve mounting a propulsion unit, and the sleeves being connectable by a bar between them during underwater operation of the device by the user.

A tablet-like device is configured to have a slightly negative buoyancy and to hold a sheet of waterproof synthetic paper, or another removable, waterproof recording sheet, onto which notes or messages or sketches can be recorded via a writing implement, in an underwater or marine environment, or another extreme or severe environment.

A tablet-like device is configured to have a slightly negative buoyancy and to hold a sheet of waterproof synthetic paper, or another removable, waterproof recording sheet, onto which notes or messages or sketches can be recorded via a writing implement, in an underwater or marine environment, or another extreme or severe environment.

A gear cabinet system having two, physically separated, sides providing compartmentalization for wet and dry storage, respectively. The first side provides a first space having ventilation functionality and anti-microbial lighting functionality for drying and sanitizing wet gear. The second side defines a space for storing and displaying dry gear.

A gear cabinet system having two, physically separated, sides providing compartmentalization for wet and dry storage, respectively. The first side provides a first space having ventilation functionality and anti-microbial lighting functionality for drying and sanitizing wet gear. The second side defines a space for storing and displaying dry gear.