Hawaii diving is slightly more strenuous than other places in the world.
The Hawaiian Islands are little specks in the middle of the huge Pacific. The water can be placid at times, but can turn tumultuous in the blink of an eye. Remember, Hawaii is known for her awesome swells and currents, which is why Hawaii is considered one of the world's leading surfing destinations. Also, the Hawaiian archipelago is a moutain chain that decends for miles beneath the surface of the ocean. So, sites are not as spread out as in places like the Carribean.