Scuba is a way of swimming underwater while breathing air from a tank strapped to your back. The word itself is an acronym: it stands for Self-Contained Underwater Breathing Apparatus. That means you carry your own air supply with you, rather than getting it from the surface through a hose.

When you scuba dive, you wear a mask to see clearly underwater, fins to help you swim efficiently, and a regulator (a device you breathe through) connected to your air tank. The tank holds compressed air, which means normal air squeezed tightly into a small space so you can carry enough to breathe for 30 to 60 minutes or more underwater.

Scuba diving lets people explore coral reefs, sunken ships, underwater caves, and the amazing world beneath the ocean's surface. Marine biologists use scuba to study sea creatures in their natural habitats. Archaeologists use it to investigate ancient shipwrecks. Some people scuba dive just for the thrill of swimming alongside fish, sea turtles, and other marine animals.

Modern open-circuit scuba technology was developed in the 1940s by Jacques Cousteau and Émile Gagnan, helping make underwater exploration accessible to many more people than before.

As a verb, to scuba means to scuba dive.