Current is something we often need to deal with when diving in open water. It can be challenging but it can also bring in clearer water and more marine life. Sometimes we can plan to do a drift dive, however usually we want to explore a site and return to the entry point. This article lists some tips for managing current on these dives.

Get low and take cover

When water flows over the bottom or any large structure, the flow next to the solid surface is slowed by friction. Divers in this friction layer are out of the worst of the current. Staying low and off the bottom requires good buoyancy control and high finning techniques to avoid disturbing or damaging the environment. Underwater structures can also provide protection from current just like surface structures can shelter us from wind. If you can get into the lee of (behind) a large structure or into a gutter or swimthrough, it can provide respite from the current to rest and recover.

Trim and streamlining

Drag increases with velocity. Current greatly magnifies the effects of poor trim and streamlining. Divers should present the smallest surface area to the water flow. Get into flat trim and streamline your body and equipment as much as possible.

Finning

Finning against current requires a strong, continuous propulsion technique such as the Flutter kick. This kick also allows the diver to stay as narrow and streamlined as possible. The Frog kick is less suitable because of the rest period between each cycle, during which a strong current will push the diver backwards. It's also recommended that divers have more 'powerful' fins that allow all of their leg strength to be utilised. Smaller, softer/more flexible fins that bend under load are not good. Stiffer, more powerful fins can lead to leg cramps if the diver is unused to them and/or kicking hard. This is something to practise before you need it for real.

Fitness

As just mentioned, your legs need to be used to working hard/swimming fast using all of the power of your fins. Cardio fitness is also important for all diving. It's even more important for diving in current. It's like going for a run instead of a relaxing stroll.

Hold on!

When descending or ascending in strong current and there is a firmly attached mooring or anchor line available, hold onto the line! The line will take you down to the site, where you can get out of the flow if needed, and get you back up to the boat after the dive. Strong surface currents are common, even if there is no current at depth. The alternative is being carried away by the current and having to be picked up, perhaps after a long, lonely drift on the surface, by an annoyed skipper and disappointed team members! No snakes for you! You can also hold on to suitable objects while underwater. Yes, we constantly say 'don't touch' but in current, sometimes carefully holding onto dead rock while staying off the bottom will allow you to catch your breath and save some breathing gas while you hold position.

Manage breathing and exertion

CO2 is the diver's enemy. More CO2 is produced when we work harder. When exerting yourself underwater, consciously adopt a deeper breathing cycle and focus on a 'proper' exhalation. Don't pant. Fast, shallow breathing will allow CO2 to build up giving you the terrible sensation that you can't get enough air. This will often be followed by anxiety that can quickly turn into panic! If you start to experience this, despite your deeper controlled breathing, try to control your natural reaction and get to a place where you can stop and rest. Continue breathing slowly and deeply. When your CO2 levels fall the anxiety should also reduce.

End the dive

Current that is excessive for you is a good reason for you to end the dive. Don't push on into current or other conditions that you're uncomfortable with. This decision is much better made early when you're not exhausted and anxious, you have more breathing gas, and you're closer to the entry/exit point.

Team diving

In current it's even more important for teams to stay in sight of each other and check each other frequently. Separation can happen quickly in current. Remember that your buddy may become tired or stressed in current. If you are fitter or more experienced, make allowances for them. Team members should stay close together at the same depth as in order to be subject to the same speed and direction of current. It's recommended that you communicate using one-handed signals. These are particularly useful when one hand is holding a line, for example. 

DSMB and other equipment

If you have to ascend away from the line in current, put up a DSMB. The skipper will be able to note your location earlier and the speed and direction of your drift. It's strongly recommended to have a large DSMB that is more easily spotted in swell and at longer distances. A height of 1.5m would be minimum and 1.8m would be better. As the current will take your DSMB as it ascends, the length of line of your DSMB should be at least 1.5 to 2 times your depth. You must be proficient in deploying your DSMB efficiently at depth, either while planted on the bottom or in mid-water, holding your depth, prior to making a controlled ascent on the line.

Jon lines are sometimes useful in current, particularly if for divers who need to do long decompression stops where gripping a line becomes fatiguing. A jon line is a line, usually around 150cm long, that attaches temporarily to a mooring or anchor line and to the diver, usually to their left shoulder or front crotch D-ring. It is secure but can be loosened and released easily (see picture).

Reef hooks perform a similar function for divers who want to attach themselves to underwater structures in current, which frees their hands and reduces the effort required to hold position. Divers who use reef hooks must be careful not to cause damage from either the hook or line.

Divers may wish to carry a personal locator beacon, a strobe light, other surface markers and/or an air horn to assist the boat to locate you if required.

General diving proficiency

Diving in current requires thought and can create a level of stress for divers. For these reasons it's good to have your diving basics well under control - buoyancy, trim, finning technique as well as being able to quickly locate and operate BC controls, reach equipment and, of course, deploy your DSMB.