Seven Of Nine is a Star Trek character, so this island is named, "One of Four" in honour of Star Trek. This is an island geocache. You will need a boat.
As with all my water geocaches, please check wind speed before you head out. This section of the Trent River is called Seymour Lake because it opens up into the size of a small lake. There is usually a west wind, and sometimes it can be very strong, which could make paddling a small watercraft dangerous. Other times, the lake can be calm and peaceful. There is a slight current in the Trent River, but you won't notice it in most places in Seymour Lake. If the predicted wind speed is going to be higher than 15 kms, you shouldn't go in a canoe or kayak. Choose your weather wisely.