Boat diving is by far the most convenient form of diving: easy access to dive sites off-shore, and minimal walking around with your gear on your back. Boats are used extensively in diving, and for good reason. While shore diving has much to offer, a number of dive sites can only be reached by boat. And while shore diving will often see you gear up a walk away from the water’s edge, and then wading into the surf. On a boat you simply jump or roll off it once you’ve kitted up, and you’re in the water. But ask any dive master and dive boat captain, and they’ll tell you that there are a few do’s and don’ts on board a boat. And sticking with these can make the whole thing run much more efficiently and comfortably.
Features that make a boat suitable for use by divers are:

• Sufficient space and stability to carry the divers and their equipment. Facilities for the divers to enter the water from the boat and board the boat from in the water. Basic marine safety equipment for the class of vessel will be required by regional or national legislation, and diving specific safety equipment may also be carried as required by legislation or the diver certification agency to which the boat operator is affiliated. This will usually include:

Basic marine safety equipment:

• marine VHF radio
• small craft emergency equipment - life jackets, flares, fire extinguishers and other equipment according to the size and operating range of the boat

Diving safety equipment: 
oxygen first aid equipment

• diving shot
• a signal flag to indicate that divers are in the water.

Day boats

These are larger, made of steel or wood, and can hold anywhere from 10 to 30 people, typically.
Accommodations onboard can range from the very basic, to the very comfortable, including showers, pantry, toilets, etc. They will not feature overnight capacity, though.
Here, you’ll often disembark using the giant stride entry, and climb back again using a dive ladder.

Live a boards

Large boats, often 100 feet or more, with full living quarters, compressor for filling tanks, room for 20 to 40 people with multi-day capacity.
With these, you live aboard (hence the name) for a longer duration, from a few days to several weeks, and dive with the boat as your primary living and excursion platform.