As the name indicates, Fern Gully is located in a north-facing hollow that holds water when other areas of the trail system are dry. This is what gives the trail its charm, but also what makes it challenging.
The trail surface can be slippery, resulting in a lot of grunts and groans while you slog up the numerous climbing turns. It's all worth it when you get to the top because you then have access to the higher-up trails. It is really the only way to reach these upper trails on this side of the trail system (on the other side, use Lodgeview - North).