Before listing a few simple ways to catch this crustacean, we must say the following. Firstly, many species of crabs are listed in the Red Book. Therefore, it is not possible to catch them everywhere and not always. If you are going to "go on a crab", ask if it is allowed to do it.
Secondly, crabs are often caught for fun. They torture the animal, and then leave it abandoned in the sand. Agree, this is not humane.
If you still want to catch a crab in order to honestly feast on your prey, then ask the fishermen or local residents in which places there are clusters of crabs. And then choose the appropriate method.
Find out where the crabs might be. Most often it is a quiet place, far from crowds. Take your snorkel, mask and fins and dive. Explore the bottom, looking under the rocks, where crabs are most often hiding. Be careful when doing this. Do not forget to bring a pair of sturdy gloves so that the beast does not hurt you while defending. The plastic bag will easily suffer from the crab's claws. Therefore, for mining, use a net with a rim.
The method is suitable for catching crabs from a boat or a pier. The crab catcher is extremely simple: a rim with a net put on it (it should hang freely from it). You need to firmly attach bait to them: meat, fish, etc. and sink to the bottom. After a while (about 20 minutes), lift the crab trap and collect the prey, which will be at the bottom of the drawn net. By the way, you can catch crayfish this way.
Here, your catch will depend on one thing: appear in the right place at the right time. The chances will skyrocket if you accurately guess the moment when the crab crawls out of the water. This usually happens in the evening or early morning, when the weather is calm and there are no strong waves. The season also plays a role.
When you decide on the timing, consider whether you can literally catch a crab with your bare hands. If the animal is in an open space, then you can do the following: drive the crab in front of the eyes with one hand (it will spread its claws to meet the "attacking" hand), and with the other lead behind it, and thus catch it.
You can also use a stick for fishing. With or without bait (to get the crab out of the rocks). Vacationers also talk about special devices for catching a crab. They are all the same stick, but with peculiar claws that need to be brought under the crab. The crustacean will catch on to them and fall into the trap.