A DPV usually consists of a pressure-resistant watertight casing containing an underwater thruster, or a battery-powered electric motor, which drives a propeller The design must ensure that the propeller cannot harm the diver, diving equipment or marine life, the vehicle cannot be accidentally started or run away from the diver, and it remains approximately neutrally buoyant while in use underwater.

If the diver does not control the DPV properly, a rapid ascent or descent under power can result in barotrauma or decompression sickness.

Fast movement and noise can frighten some fish into hiding or swimming away, and the DPV is bulky and affects precise manoeuvring at close quarters.

Since the diver is not kicking for propulsion, they will generally get colder due to lower physical activity and increased water flow.

The name was commonly used to refer to the weapons that Italy, and later Britain, deployed in the Mediterranean and used to attack ships in enemy harbours.

[9] The idea was successfully applied by the Italian navy (Regia Marina) early in World War II and then copied by the British when they discovered how effective this weapon could be after three Italian units successfully penetrated the harbour of Alexandria and damaged the British battleships HMS Queen Elizabeth and HMS Valiant, and the tanker "Sagona."

[10][11] The Motorised Submersible Canoe (MSC), nicknamed Sleeping Beauty, was built by British Special Operations Executive (SOE) during World War II as an underwater vehicle for a single frogman to perform clandestine reconnaissance or attacks against enemy vessels.

[13] For long-range missions, SDVs can carry their own onboard breathing gas supply to extend the range of the swimmer's scuba equipment.

[citation needed] In the latter usage, SDVs can stealthily plant mines and other bombs on ships or port infrastructure and then retreat to a safe distance before detonating the explosives.

[15] One type of SDV—the Mark 9 SEAL Delivery Vehicle—was also capable of firing torpedoes, giving it the standoff ability to attack from up to 3 nautical miles (5.6 km) away.

[14] The origins of the SDV stems from the Italian human torpedoes and the British Motorised Submersible Canoe used during World War II.

The human torpedo was used to great effect by commando frogmen in World War II, who were able to sink more than 100,000 tons worth of ships in the Mediterranean alone.

Some Farallon and Aquazepp scooters are torpedo-shaped with handles near the bow and a raised seat at the rear to support the diver's crotch against the slipstream.

[20] DPVs currently in service include: Swedish firm Defence Consulting Europe Aktiebolag (stock company, often abbreviated as DCE AB) has developed a family of SDV of modular design, all of them based on the same basic frame and general design principle, and current available versions include:[26] white 2015 human crew SDV with 30+ kn on surface and can be parked on the sea floor.

[28] After purchasing US submersible manufacturer Seahorse Marine, Emirate Marine Technologies of United Arab Emirates has developed four classes DPV/SDV, all of them built of glass reinforced plastic and carbon composite materials: white 2015.75 tonne 6 to 8-person SDV developed by Columbia Research Corporation built of fiberglass.

There is also a multi-beam obstacle-avoidance sonar to distinguish targets while the integrated communications suite includes an underwater telephone and a VHF radio.