In non-competitive diving, a dolphin dive is a form of rapid entry used by lifeguard

Lifeguard

A lifeguard supervises the safety and rescue of swimmers, surfers, and other water sports participants such as in a swimming pool, water park, or beach. Lifeguards are strong swimmers and trained in first aid, certified in water rescue using a variety of aids and equipment depending on...

s to quickly traverse stretches of shallow (waist - chest deep) water. To perform a dolphin dive:-

• The rescuer runs to a point where the water is roughly-waist deep. Before forward momentum can be slowed...
• The rescuer leaps forward in a dive position, arching his body to break the surface and reach down towards the sand.
• The rescuer then tucks his feet underneath his chest to where his hands were, and begins the next dive.

Dolphin dives are performed in rapid succession until the water is neck-deep, at which point the rescuer transitions into an appropriate swimming stroke, such as heads-up front crawl

Front crawl

The front crawl, forward crawl, or freestyle is a swimming stroke usually regarded as the fastest of the four front primary strokes. As such, the front crawl stroke is nearly universally used during a freestyle swimming competition, hence the synonymously used term "freestyle". It is one of two...

 or breaststroke

Breaststroke

The breaststroke is a swimming style in which the swimmer is on his or her chest and the torso does not rotate. It is the most popular recreational style due to its stability and the ability to keep the head out of the water a large portion of the time. In most swimming classes, beginners learn...

.