When you enter Acadia National Park head towards Sand Beach and Otter Cliffs. Follow Park Loop Road down to the Otter Point Parking. Park in this lot and exit the lot at the opposite end you entered from. Cross Park Loop Road to the trail head for the Ocean Path. From there the ceremony will be happening at the first overlook you come to, roughly 10 ft.
The attire is semi-formal but please wear what you are comfortable with as you will be on a trail. This trail is very flat and well maintained, however it is probably best to avoid heels and any slippery shoes. Also please be prepared for any weather, as it is an outdoor ceremony.