Big pelagics and schooling fish are usually found in areas of strong currents. This is because currents bring plankton which attract small fish, which, in turn attract larger predatory fish and pelagics.
The thought of diving in a strong current can cause some divers to break out into a cold sweat. Be armed with knowledge by following these tips and you will be able to dive comfortably and safely in currents…
1. Listen to the dive briefing and ask questions!
The dive guides have extensive experience and knowledge of the dive sites and know what to look for. They will give you a detailed briefing about the currents – what to expect and what to do should you encounter them. They know the areas prone to currents and will inform you accordingly.
2. Go straight down:
If there is a current and the skipper does not anchor or use a drop line, it is best to do a negative entry and go straight down, keeping an eye on the dive guide at all times. You might need to fin hard to get to the bottom (where the current is usually weaker). This way you stand less chance of missing the reef and losing the group. It is always best to descend a drop line, going down slowly, hand over hand and meeting your group at the bottom.
3. Stay low:
Currents closer to the surface tend to be stronger than the currents on the bottom. If your dive involves a wreck or big reef, moving behind it in the lee of the current will protect you and you will have a far more comfortable dive. At some stage you might even need to pull yourself along the bottom by grabbing hold of dead coral and rocks. Be careful where you put your hands and be careful that you are not grabbing a stone fish or other marine creature by mistake.
4. Watch the fish – they are the experts!
Most fish swim into the currents and hid between rocks and corals. Try to mimic them where you can, to stay out of the current.
5. Leave your camera behind:
If you know the current is going to be incredibly strong, it is probably best to leave your heavy camera rig behind on the boat. It will cause drag and make swimming against the current much harder. If you do decide to take it along, make sure you are able to attach it to your BCD in order to free up your hands.
6. Finning techniques:
You will need to adjust your finning technique as frog kicks do not have enough power in them. Rather use a stronger and more traditional finning technique. Stronger and less flexible fins work best in currents – split fins are not ideal.
7. Stop, relax and breathe:
If you get caught in a current, are getting tired of finning against it, try to hold onto a dead piece of coral. Stop a while, relax and breathe until you feel you can go on.
8. Know when to call your dive:
If you feel you can’t go on, end the dive. Signal to the dive guide (if still close by) and your buddy (who, if they are a good buddy will still be close by!). You and your buddy should start your ascent close together and deploy your smb so that the boat can come and collect you. If diving a wall, swim away from the reef whilst on your safety stop so that the tender can reach you without hitting the reef!
9. Always use an SMB:
Currents on the surface can drag you away from the dive site, making it difficult for the dive boats to see you once you have surfaced. Everyone should have an SMB so that lone divers / buddy pairs can be spotted.
Types of Currents:
Currents do not always travel in the same direction from top to bottom. Sometimes, surface currents change speed and/or direction midwater. When diving on a wall, you can also come across up currents and down currents and you need to know what to do should you encounter them.
These are are surface and mid water currents and are the most common you will come across. There are two different ways of diving them, the first being the preferable:
Going with the Flow:
Drift diving (going with the flow) is relaxing and enjoyable. It is important to follow the dive guide and stay with the group. To slow yourself down, you can hold your body at 90 degrees to the current, causing more drag.
Fight the Stream:
Wrecks are a good example of this – you need to stay on the wreck for the duration of the dive and currents can sometimes make this difficult. Descending on a line (hand over hand) is the best way to make sure you get to the wreck. It is quite normal to start your dive swimming into the current whilst you still have energy and plenty of air. Usually when one third of your gas supply is gone, you would usually turn and simply drift back towards the descent line, where you will do your ascent to the boat.
You are likely to first spot a down current if you see bubbles surrounding the divers in front of you. If the little fish are pointed head up and the soft corals are sweeping downwards, be aware of what’s ahead! They are caused by water sweeping over the top of a wall or a steep slope which can cause a strong current heading down to depth.
They are not terribly common, but being caught in one can sometimes be quite terrifying and it is important to keep your cool!
What to do if you encounter a strong downward current:
- Stay calm, stop, think and act.
- Grab hold of something on the reef (preferably something not living!) to stop the descent.
- As they are caused by reef topography where something is funneling the water down from the surface at a particular point, they often only occur in sections of the reef so it may be possible to swim through it and out the other side.
- If the current continues, you might need to crawl up the reef hand over hand. This is bad for the reef but if the situation is desperate, you might need to do it!
- Some advocate swimming out, away from the reef as at some point the current will cease but you might need to go far out and the current might become stronger, by which point you will no longer have reef to hold onto.
- If the situation becomes serious, you can inflate your BCD and fin upwards, but be very careful when doing this as if the current suddenly stops, you might have an uncontrolled ascent on your hands. Be prepared to dump air quickly!
- Only drop your weights as a last resort. The problem with this is that once you escape the current, you will be more positively buoyant than you normally are and this will cause difficulty with making a safe, controlled ascent and you won’t be able to do a safety stop.
Strong upcurrents can cause divers to ascend too quickly and make safety stops impossible. This could also cause diving injuries such as DCS or an embolism.
You will see the fish swimming down as they work to stay in place in the face of the up-current that coincides with the ridge.
The best way to handle these are to swim downwards, away from the reef and dump your air. Once you are deeper, it is likely that you will be less effected by these currents and will be able to continue your dive.