Zodiac boats also put you right where the action is. They hold six people plus the captain and can go almost anywhere. You are almost certain to see dolphin. Larger boats such as Gypsy, Vagabond, Adventure and others provide a more stable platform with amenities such as a bathroom, soft drinks and snacks. If you go on your own, look for a shrimp trawler anchored with its nets raised.
Chances are they are cleaning shrimp, which attracts small fish, which in turn attract dolphins.
You might well be treated to an unforgettable sight. Bang on the side of your boat to call him - he might come close enough to touch. Consider the distance from the marina to the area you will be going. You don't want to spend all your time getting there and getting back. Deer are so plentiful on Hilton Head, especially in the Plantations, they are considered pests by some people.