DIVING IN CURRENTS-some useful info and tips
This should be called DRIFT diving--which means going in the same direction as the current--instead of going against the current. If you've never been in a current the thought of doing it can be pretty intimidating. However, mild ones can be very enjoyable to beginning divers because you just relax and go with the flow. Follow your buddy, the boat follows your bubbles, and everybody has a wonderful time.
The advantages and disadvantages of drift diving: If you do these correctly it's a low energy trip that allows you to see a whole lot of an area without using much air. Large marine animals, like sharks, turtles, mantas, schools of fish, etc., don't seem to be as concerned about that noisy bubble machine (you) as they are when you can swim at them from any direction with no current.
The flip side of this is that you miss a lot of small life, and the hazards of loss of control and any efforts to work against the currents are high energy, air sucking, and stress producing.
When you look up and don't see your bubbles, you're in a current! Currents are usually generated by wind and tides or a combination of the two. In certain areas, such as "Ant Atoll" in Pohnpei and almost any dive site in Palau and Yap, the currents are almost always due to tidal action and are fairly predictable. Sometimes they are quite mild, but in many instances they can "kick it up a notch or two" very fast. Preparation and knowledge go a long way to having an enjoyable dive.
Recognizing that there is a current is the first step. Here's some pretty good indicators:
--fast moving surface water while the boat is stationary on a mooring
--movement of floating material on the water or in the water
--movement of divers away from the boat rapidly on entry
--bubbles moving away from a diver at an angle underwater
--if the plant life and fish are facing one direction.
How to dive in a current. We're not going to cover everything here, but these tips will certainly help:
-plan your air and bottom time to have a lot of air in reserve, and never plan a decompression dive in a current.
-on descent DON'T decide to fix your mask strap, find your reg, etc. after you enter. Instead, get your butt down to the depths you are going to dive at as fast as you can. The saves you going past where you want to dive and attempting to get back to it by swimming against the current.
-study the bottom or marine life to determine which way the current is going. Go with it.
-adjust your buoyancy to keep neutral or slightly negative.
-wear gloves. If you have to stop and see something you can grab on to a rock. Try and get behind a large one or a coral head as there is much less current effect there.
-always have and use a safety sausage (tube). Practice with it before you go on the once in a life time dive or trip.
-once on the surface STAY on the surface. The dive boat may be busy picking up other divers, or may not have seen you yet. Stay there.
USE THE BOTTOM CURRENT: The contour of the ocean bottom will change which almost always causes the currents to change, often dramatically. In most areas the current is actually less near the surface than on the bottom.
A diver can adjust their speed by moving to the bottom, and just drifting above it a depth that's comfortable for you.
STOPPING IS THE PROBLEM! Everything is fine when you "floating" along, but it can all change when you decide to stop and take a photo, etc.
Look ahead for large boulders, rocks, or coral heads and duck in and settle right behind them on the opposite side of the current movement. There is usually no current, or very slight current "pull" here and they make very good resting places to catch your breath, get a few photo's, etc.
Going against the current: As divers moves through the water we encounter resistance, and this increases dramatically with the velocity of the current as it passes over the body. As we work against the current our there is a huge increase in air consumption, particularly when we are trying to swim against a current. However, in some cases (such as the current changing to the opposite direction) you have no choice but to go against it.
"Bottom crawling" is an alternative when it's just too hard to swim against a current. This is easily done in rocky areas but can be a real challenge in sandy bottoms, where a good dive knife comes in handy as an anchor.
Getting close to the bottom and using your fingers or dive knife to stabilize you is usually all you need to hold your position.
Required gear for currents or drift diving. DON'T think that if my buddy has this it's ok. Get them for yourself and practice with them.
--safety sausage or tube with at least 25' of good line. Get rid of that tiny line that comes with most and replace it with line the dive shop recommends.
--a small dive mirror that you can put in your bc pocket before the dive.
--a whistle on your bc
--some type of long sleeve protection. A .5mm full suit is a great protection against the millions of "no-see-ums" that sting that are almost always in currents.
We are a sure there's more that others will add, but this is a good primer for you.