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Scuba Diving Dictionary

Scuba Diving Dictionary Landing Page Description

Whether you’re a new diver or one who’s returning to the sport, or even if you’re a frequent diver with the occasional question that needs answering, you’ll discover that our dive dictionary is a very useful scuba diving resource. Here, you’ll see a comprehensive list of scuba diving terms, along with acronyms and so much more.  Using our scuba dictionary to locate diving terms is quick and easy; just choose a letter or number and click on it, or simply enter a keyword to find its definition. Be sure to contact us if you’re looking for diving terms, acronyms, or any other type of scuba-related jargon you cannot uncover here. We’ll do our best to keep updating our diving dictionary so you can find the answers you need, when you need them.

L

League

A former measure of distance by land using the nautical measurement unit which is approximately 3 miles in the USA 

LED

Light Emitting Diode

Leeward

On or facing toward the “lee side” or side sheltered from the wind

Lesion

A wound or local injury to an organ or tissue

Lifeline

A rope or line between the diver and tender which is by a diver to send signals to the surface, to assist in a normal ascent, and to retrieve the diver during an emergency 

Lift Bag

A specialized, air-tight bag used by divers to lift heavy, submerged objects to the surface

Light Breeze

A wind force of four to six knots; number two on the Beaufort scale

Lionfish

A brightly colored tropical Pacific scorpionfish that has elongated spiny fins which does not camouflage itself and makes little to no effort to avoid humans

Littoral

The zone lying on or along the shore of a body of water between the high and low water marks

Liveaboard

A recreational dive boat that is equipped to conduct extended dive trips without returning to port which provides divers with comfortable accommodations, tasty meals, and unlimited diving

LNG

Abbreviation for liquified natural gas, mainly methane and ethane; which is stored at cryogenic temperatures so that it can be easily transported

Log Book

Maintained by a diver, a recorded list of dives which may be used to show proof of experience

Low Pressure Hose

A hose that connects the second stage to the first stage of a regulator 

Low Water

The lowest point in a body of water that is reached by falling tide

Lower High Water

The lower of the two high waters on any tidal day in areas with mixed tides

Lower Low Water

The lower of the two low waters on any tidal day in areas with mixed tides 

LPM

Abbreviation for liters per minute; a measurement of the flow rate of a gas or liquid

Lungs

Two sponge-like breathing organs situated in the chest that consist of approximately 750 million alveoli which remove carbon dioxide from and bring oxygen to the blood

LWL

Abbreviation for low water level

M

M.S.

Abbreviation for military specifications

Macrophotography

Photography that produces photos of small subjects that are often larger than life size; macro accessories attached to the underwater camera are used divers to capture such images

Magneto

An small electrical device with a permanent magnet that generates periodic pulses of alternating current

Main Deck

The principal strength deck in a vessel that often extends the full length and width of the ship

Mal De Mer

Seasickness

Mandarin Fish

A freshwater fish, also known as a Chinese perch, and not to be confused with the unrelated saltwater mandarinfish; has a yellow, green, or brown back with irregular black spots and lives in China

Manifold

A pipe or chamber with multiple openings that is used to connect various cylinders to one inlet or outlet

Manometer

An instrument for measuring the pressure of liquids, gases, and vapors both above and below atmospheric pressure

Marfan's Syndrome

A genetic disorder of the connective tissue caused by a defect or mutation in the gene that often determines the structure of fibrilin-1 protein

Marine Biology

The scientific study of plants and animals that live in the ocean or other bodies of water

Marine Life Hazards

Sealife considered to be a danger or hazard to divers 

Mask

A piece of diving equipment worn by scuba divers over their face which provides an air pocket in front of their eyes so that light enters normally, allowing better vision underwater

MLW

Abbreviation for mean low water

Moderate Breeze

Using the Beaufort scale, a wind with a speed between 13 and 18 miles per hour 

Moderate Gale

Using the Beaufort scale, a wind with a speed between 32 and 38 miles per hour

MSW

Acronym for meters of seawater

Mucus

The viscous, slimy secretions that moisten and protect the mucous membranes

Multiple Sclerosis

An autoimmune disease of the central nervous system which affects an individual’s movement, ensation, and bodily function; these symptoms are often similar to those experienced by DCS sufferers

Myalgia

Generalized muscle pain or tenderness

Myocardium

The cardiac muscle that makes up the middle layer of the heart wall

Myopia

Near sightedness; also known as short-sightedness

N

NASDS

National Association of Scuba Diving Schools

NAUI

National Association of Underwater Instructors

Nausea

An unpleasant sensation in the stomach which often culminates in vomiting

Navy SEAL

A member of the US Navy trained for unconventional warfare by air, land, or sea; a military diver

Necrosis

The death or decay of a majority of the cells in an organ or tissue as a result of injury, disease, or the failure of blood being supplied to the area

Nematocysts

Stinging cells in the tentacles of certain coelenterates, including jellyfish, that contain a barbed, threadlike tube that provides a paralyzing sting when injected into their attackers and/or prey

Neoprene

An synthetic polymer that resembles rubber, often used in diver wetsuits, that is resistant to oil, heat, and overall weathering

Nervous System

A network of nerve cells in the brain, spinal cord and other parts of the body that transmit nerve impulses among the body

Neuromuscular

Relating to the nerves and muscles or to the relationship that exists between them

Night Diving

Scuba diving that takes place at nighttime

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