The Uga Shrine is located on an island in the middle of Lake Nojiri. The only way to access it is by a taking a cruise boat from Nojiri city. The cruise does a brief tour of the lake before stopping on the Island. You can spend as much time as you like visiting the shrine since you can hop on subsequent cruises as well for the return trip.
Mount Kurohime is located in the northern part of Nagano prefecture. When I visited with my girlfriend’s family, there were really nice gardens in full bloom. We took the cable-car to go half-way to the summit where we enjoyed a fantastic view of Lake Nojiri.