Scuba diving is an underwater activity that involves using a self-contained breathing apparatus (SCUBA) to explore the ocean.

What it is
Scuba diving allows divers to breathe underwater for longer periods of time than snorkeling or free diving. Divers carry their own air supply, usually compressed air, which gives them more independence and movement than surface-supplied divers. 

What the equipment is
The term "scuba" is an acronym for "Self-Contained Underwater Breathing Apparatus". Divers breathe through a mouthpiece attached to a tank of compressed air. 

What it's like
Some say there's nothing like scuba diving. You can try scuba diving for the first time with a Discover Scuba Diving experience, where you'll put on the gear and breathe underwater in a pool. 

How to get certified
Scuba-certifying agencies offer training courses for beginners and experts. Courses include classroom instruction and water training. 

Safety
Most agencies recommend diving in a buddy system of two or three divers. 

The maximum depth for recreational scuba diving is 40 meters (130 feet). Divers who want to go deeper than this need technical diving skills and certifications. Technical divers can descend to depths of over 90 meters (300 feet). 

The recreational diving limit is based on safety and is due in part to the effects of nitrogen narcosis, which can occur at depths as shallow as 30 meters (98 feet). Nitrogen narcosis can cause drowsiness, headaches, dizziness, vomiting, and even loss of consciousness. 

Beyond 40 meters, divers need to make decompression stops and may use different gas mixtures. For example, at depths beyond 50 meters, divers may dilute nitrogen with helium to dive deeper more clearly. However, helium can cause high pressure nervous syndrome (HPNS) at depths around 150 meters. 

To enroll in a PADI Scuba Diver course (or Junior Scuba Diver course), you must be 10 years old or older. You need adequate swimming skills and need to be in good physical health. No prior experience with scuba diving is required, but you can try it first throughthe Discover Scuba® Diving program.

The first step to scuba diving is to enroll in a scuba diving certification course at a certified diving school or center: 

Choose a dive center
Look for a center affiliated with a recognized training agency, such as the Professional Association of Diving Instructors (PADI), Scuba Schools International (SSI), or the National Association of Underwater Instructors (NAUI). 

Take an Open Water Course
This entry-level course teaches the fundamentals of scuba diving, including theory, dive skills, safety, communication, and navigation. 

Get certified
Earning a scuba diving certification ensures a safe dive and makes it easier to rent scuba gear. 

Prepare for the course
Some dive centers will send a medical questionnaire to evaluate your physical readiness. If you have certain health conditions, you may need a doctor's approval to participate. 

You can also try a discover scuba diving experience to get an introduction to scuba diving. This experience usually includes a briefing on safety and an introduction to the diving equipment.