The Red Trail from Whale Cove to Swallowtail is the trail my wife and I hiked when we visited Grand Manan for the first time in the mid-90s. I've always enjoy this particular section of the trail where it hugs the coastline, giving some nice glimpses of the water and Seven Days Work through the trees.
The container you're looking for is a large, natural one but not a dominant part of the ecosystem in this area of the island. It is hidden just off the trail and shouldn't involve any real bushwhacking. The inner cache container has a log, pencil, and a few trinkets for kids. Please don't put the pencil in the zip-bag to avoid puncturing it.
See the note in the additional waypoints below for information on the park fees, parking and free access the trail and cache.
A few safety notes. This coastal trail is ungroomed and rugged. In places it follows the coastline close to the cliffs. The cache is located off the trail away from the cliffs so you need not search there. Avoid approaching the cliff edges as they may be unstable and prone to crumble. Also, keep in mind that long ago this area was farmland. The remains of an old wire fence runs along the edge of the dry stream bed. I've done my best to clear it away, wrapping loose ends embedded into a spruce tree around the trunk and covering the rest with brush where they run back into the thicker forest. And finally, the ticks. Grand Manan has reportedly a high concentration of deer ticks which may carry lyme disease. Although I've never seen or pickup one on the island I encourage you to dress appropriately and check yourself over after your hike. Be safe and have fun.
Congratulations to CacherCook, sandy queen, rockcrawler04, and victoriacaches on the FTF. Hope you all have a great visit on Grand Manan and sorry our vacations did match up better so we could attend your event.