Rip tides (properly known as rip currents or undertows) cause more tourist deaths in Costa Rica than all other reasons put together. Tripped by alcohol, weak swimming skills, misinformation, and perhaps sudden weather changes, several tourists secumb to Neptune's quiet hidden killers each year. 90% of Costa Rica's 150 to 200 total drowning deaths each year occur at 5% of Costa Rica's beaches, and 80% of those deaths are rip tide assisted. Understanding rippers allows you to safely enjoy the ocean.
Caused by a build up of higher water along the coast brought in by waves, invisible channels of water from 20 to 100 meters wide begin to flow backwards towards the sea to equalize the sea level. It is like a swift moving river taking everything in it out to sea!
There are three parts to the rip. The 'feeder current' runs parallel to the shore. If you notice yourself rapidly passing beach landmarks, you are in one. The 'neck' is where the feeder current makes a 90% turn and starts to head outward. At this point, if you can still touch bottom, walk parallel to the shore helping the waves push you closer to shore.
If you are over your head, relax, lie back and float for a minute or so with your hips up and your face out of the water. The ripper will take you for maybe a hundred or two hundred meters out to the head, where the current weakens usually just beyond where the waves begin to break. Now calmly swim parallel to shore, relaxing and stretching your strokes for a while until you are out of he ripper. At this point take advantage of the waves and head to shore at a 45 degree angle to the neck. Often with the strong waves, there will be surfers around, using the ripper to get back to sea. If you can catch their attention and pull them away from their nurly curls dude, a surf board is a very reassuring thing to hold on to. Never try and fight the current. The secret is to relax, float, gently kick from the hips, and conserve your energy, you'll be out in a few minutes, and sorry for the inconvenience!
From the shore, a ripper may look like a muddy stream, it may not have breaking waves, when it is surrounded by breakers, sometimes if has foam along the head and neck, and often river mouths make ideal rippers. Near a hard white sand shore they are the hardest to see. They are strongest at high tide, and can be permanently located, moving along the shore, and even intermittent. Check locally before entering rough waters.
Keep this info and pass it on to others, it could save anyone's life.