Can I join a shop trip if I am not a member or student there?

Usually yes if there is space. Ask the host directly; some hold spots for their own students first and open the rest later. You will be diving with people who already know each other, so expect to be pulled into the group fast.

What happens if the group does not fill?

Most hosts book a block of rooms and boat spots with a release date. If the block does not fill by then, the trip either runs smaller or the host cancels and refunds deposits. Ask for the minimum group size before you pay.

Do I need to bring my own gear?

Bring your own mask, computer, and exposure suit at minimum. Rentals are usually available through the operator, but group rates rarely include them, so price that in before you compare trips.

Dive Club and Local Dive Shop Group Trips

You already know who you want on the boat. These trips are anchored by a dive shop, club, instructor, or group leader who has done this before and will do the herding so you can just dive.