A hydrocycle is bicycle

Bicycle

A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....

-like watercraft

Watercraft

A watercraft is a vessel or craft designed to move across or through water. The name is derived from the term "craft" which was used to describe all types of water going vessels...

. Power is collected from the rider via a crank

Crankset

The crankset or chainset , is the component of a bicycle drivetrain that converts the reciprocating motion of the rider's legs into rotational motion used to drive the chain, which in turn drives the rear wheel...

 with pedals

Bicycle pedal

A bicycle pedal is the part of a bicycle that the rider pushes with their foot to propel the bicycle. It provides the connection between the cyclist's foot or shoe and the crank allowing the leg to turn the bottom bracket spindle and propel the bicycle's wheels...

, as on a bicycle, and delivered to the water or the air via a propeller

Propeller

A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...

. Seating may be upright or recumbent

Recumbent bicycle

A recumbent bicycle is a bicycle that places the rider in a laid-back reclining position. Most recumbent riders choose this type of design for ergonomic reasons; the rider's weight is distributed comfortably over a larger area, supported by back and buttocks...

, and multiple riders may be accommodated in tandem

Tandem bicycle

The tandem bicycle or twin is a form of bicycle designed to be ridden by more than one person. The term tandem refers to the seating arrangement , not the number of riders. A bike with two riders side-by-side is called a sociable.-History:Patents related to tandem bicycles date from the late 19th...

 or side-by-side

Sociable

The Sociable or Buddy Bike or Side By Side Bicycle is a bicycle that supports two riders who sit side by side.This type of bicycle should not be referred to as a tandem bicycle as "tandem" is defined as: "a group of two or more arranged one behind the other ..."-History:The Sociable is said by some...

. Buoyancy

Buoyancy

In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

 is provided by two or more pontoons or a single surfboard

Surfboard

A surfboard is an elongated platform used in the sport of surfing. Surfboards are relatively light, but are strong enough to support an individual standing on them while riding a breaking wave...

, and some have hydrofoil

Hydrofoil

A hydrofoil is a foil which operates in water. They are similar in appearance and purpose to airfoils.Hydrofoils can be artificial, such as the rudder or keel on a boat, the diving planes on a submarine, a surfboard fin, or occur naturally, as with fish fins, the flippers of aquatic mammals, the...

s that can lift the these floatation devices out of the water. Brand names include Seacycle, Hydrobike, Water bike, and itBike. Kits exist to convert an existing bicycle into a hydrocycle temporarily.