Your first drift dive: what Open Water divers should know

On a drift dive you enter the water and let the current carry you along a reef or wall, while the boat follows your bubbles and picks you up wherever you surface. You don't swim back to an anchor line. Done well, it feels like flying, and it is how some of the best-known reefs in the world are dived.

Currents also bring the nutrients that attract fish, which is why the busiest sites are often the ones where the water moves. That is the trade: more life, less room for mistakes.

• Buoyancy control. You need to hold a depth without kicking, and stay off the reef when the current pushes you toward it.
• A quick descent. Some sites use a negative entry, where you descend straight away so the group isn't scattered at the surface. Practise venting your BCD and equalising early.
• Air awareness. Working against current uses more gas. Check your gauge more often than usual and agree a turn pressure with your buddy.
• Deploying a surface marker buoy (SMB). On a drift dive the buoy is how the boat finds you. Practise inflating it from a few metres down on an easy dive before you need it.

If any of these feel shaky, an Advanced course or a few guided dives in mild current will help more than reading. The certification guide explains what each card covers.

The briefing is where you learn how this particular site behaves. Listen for these points, and ask if any are missing.

• The expected direction and strength of the current, and what to do if it changes.
• The entry: negative or not, and where to meet underwater.
• Maximum depth and dive time, and whether there are down-currents to watch for.
• Whether reef hooks are used, and where it is acceptable to hook in.
• The ascent: who sends up the buoy, and whether the group surfaces together.
• What to do if you lose the group: usually search for about a minute, then ascend with a safety stop and deploy your buoy.

Stay close to your buddy and the guide. In current, a gap of a few metres can grow quickly, and you can't swim back to close it. Keep slightly above and behind the guide so you can see where they are heading.

Use the reef to your advantage. Behind large rocks and coral heads the water is calmer, and dropping a little lower near the reef often takes you out of the strongest flow. Don't grab coral to stop; if the site uses reef hooks, the guide will show you where to place one on bare rock.

If you feel the water pulling you downward, with bubbles going sideways or down, swim away from the wall toward open water rather than straight up, and add a little air to your BCD. Down-currents are usually narrow and weaken away from the reef.

Do your safety stop as normal, with your buoy up so the boat can see you. At the surface, stay together, keep your buoy inflated and wait for the boat to come to you. Many divers also carry a whistle, and some carry a personal locator beacon on remote trips.

These are the destinations we rate as having moderate or strong current. Start with the moderate ones and build up. Destinations not listed here are mostly mild.

• AnilaoModerate · Mostly mild at the macro sites; can be strong at exposed points such as Beatrice Rock and Mainit Point
• AzoresModerate · Moderate; offshore seamounts can be strong
• Belize Barrier ReefModerate · Mild on the sheltered reefs; strong with surge at exposed points such as The Elbow
• CozumelModerate · Moderate to strong drift on most reefs
• FijiModerate · Moderate in the passages, where the soft coral is best
• MalapascuaModerate · Usually mild to moderate; can pick up on the shoals and around Gato Island
• MaldivesModerate · Moderate to strong in the channels between atolls
• Raja AmpatModerate · Moderate to strong at many sites
• Similan IslandsModerate · Mild at most sites, strong at a few exposed pinnacles
• SipadanModerate · Mild to strong depending on the site and tide
• Tubbataha ReefsModerate · Moderate on the walls, stronger at some points
• Cocos IslandStrong · Strong, with surge; open-water descents and blue-water drifts
• GalápagosStrong · Strong, with surge; negative entries and reef hooks are common
• KomodoStrong · Strong, with down-currents
• Nusa PenidaStrong · Strong and changeable drift currents, with down-currents at some sites
• PalauStrong · Moderate to strong; down-currents at some sites
• Rangiroa and FakaravaStrong · Strong tidal currents in the passes; dives are timed for the incoming tide
• Socorro IslandsStrong · Strong, with surge on the pinnacles