Plattsburgh sits on the banks of Lake Champlain, not a Great Lake but very impressive and there are a group of people petitioning to get it turned into one of The Great Lakes. The Lake Champlain Ferries have several different routes, we took the Plattsburgh-Grand Isle, Vermont route to take a more scenic drive into Canada and it was. It was a great idea (mine, of course!). We enjoyed a short ramble through the Vermont countryside and then crossed over into Canada at a very small border crossing with no other traffic in sight. The ferry from Plattsburgh to Grand Isle only took 12 minutes but it was a very scenic and only costs $10.00
Address: 87 to exit 39, follow signs 5 miles to ferry
Website: http://www.ferries.comAdd to your Trip Planner
Ausable Chasm is located 20 miles to the south of Plattsburgh on US Route 9. It has a spectacular waterfall by the Route 9 bridge. It also has steep cliffs with rushing water. It is about 1 1/2 mile long. I personally did not take the tour here because of time constraints. The tickets were $13 to take the walking tour of Ausable Chasm. From the little bit I saw of it, the scenery was spectacular.
Directions: US Route 9, take exit 34 off I-87 (NY Route 9N) to Route 9 North