What does trident-toters only mean?

Trident-toters only is a phrase that is used to refer to people who are armed with tridents. Tridents are a type of spear that has three prongs, and they are often associated with the sea and with Poseidon, the Greek god of the sea. The phrase "trident-toters only" is therefore a way of saying that only those who are armed with tridents are allowed to enter a certain area or participate in a certain activity.