Currents are the movement of water in one direction that may change direction as tides or wave actions change. Divers need to be aware of the effects of currents and understand the limitations of moving in a current.
Waves generally approach the shore at slight angles and rush up the beach at an angle and down the beach with the slope, resulting in the net water movement being along the shoreline. If you didn’t account for this, you will be pushed away from your intended exit point. So, begin your shore-entry dive up-current from your exit point, or dive into the current and drift back to the exit on your return. A dive that carries you along the reef or shore is called a drift dive. You should consider additional training for drift diving, especially in fast currents.
The volume of water brought to the beach by waves needs to escape, and it will generally do this along the easiest path, often creating narrow streams of water running out to sea. A sand bar or shallow reef can help cause rip currents by hindering the easy exit of water and instead funneling it to form a rip current. Rip currents tend to be very strong and can rip you away from the shore quickly. They are usually formed on beaches with a lot of waves.
You can usually see a line of turbid, foamy water moving away from shore, and it often will disrupt the waves where it rushes seaward. If you get caught in a rip current, establish neutral buoyancy and swim across the narrow area of moving water. Never try to swim against a rip current!
When diving in a mild current, always start your dive into the current. Then on your return, the current can assist you back to the shore or dive boat. Avoid surface swims against a current; they will tire you. Rather, swim along the bottom, where the current is usually weaker, if it is in reach of your dive plan. If a current takes you past your exit point, establish positive buoyancy, signal to the dive boat or surface support for help, and wait until you are collected.
You can use currents for drift diving. This type of diving requires more training and practice. You need to follow safety rules and keep a good eye on your buddy. It is much easier to get disoriented while drift diving.