A tall but typically low-flowing waterfall, Gray Mares Tail is nonetheless a worthwhile stop a short distance from St Marys, just before the road starts descending St Marys Pass.
To find the falls, look for an easy-to-miss pullout with a sign marking the St Marys Pass State Reserve on the left. From here a sign points to Gary Mares Tail, just a 5-10 minute walk away. The short and easy trail winds through the forest, before coming to a lookout platform overlooking the top section of the falls.

While the part that can be viewed easily is a decent 20 metre drop, the creek looks to keep cascading further below, and the total height of the falls is likely to be well in excess of 50 metres.