Proper training and proper equipment.
Proper training usually means certification by a recreational Scuba diver training agency, like PADI, NAUI, BSAC or SDI.
Proper equipment usually means (at a minimum):
A bubble of divers
Shadow Divers was created in 2004.
Skin divers are people who dive into the ocean without using special equipment, unlike Scuba divers.
There were no divers in the middle colony.
The duration of Hell Divers is 1.82 hours.
Shadow Divers has 397 pages.
Divers dive in the sea/water, not earth.
Here are three sentences including the word 'divers': "There are a lot of divers in the river because they are looking for a missing body." "If there is a shark in the water it can be dangerous for divers." "Divers get to look very closely at fish." *The above examples refer to divers as a noun if one is speaking of person's who dive. Divers (adjective): various. "The state fair offers divers amusements for the whole family. Divers (pronoun): an indefinite number more than one <he raked a divers amount of leaves> Diverse (which one may find similar is not): differing from one another: unlike <people with diverse interests> <his message appealed to a diverse audience>
Tactical Divers Group was created in 1952.
Edward Divers died on 1912-04-08.
Edward Divers was born on 1837-11-27.
Hell Divers was created on 1932-01-16.