GPS - Global Positioning System receivers can determine your absolute position, track your course, give time averaged speeds, etc. You still need a compass to find a bearing. Also, electronics can fail, so you will need other navigation techniques. You should consider using a waterproof GPS bag . Tide Tables - We have significant tides on the East Coast, and tide tables allow you to plan your outing to minimize fighting the currents.
Tables are available on the internet .
Having food is important to keep your energy from flagging. Hat, Sunblock, Sunglasses - We don't want to fry in the sun. Sun stroke is a risk, and don't forget the damage UV radiation can do to skin. Whether you wear sunglasses or prescription glasses, these will keep your specs on your head. Consider it required gear if you need prescription glasses.