Ride a bus straight into a lake
On an amphibious bus, often called a duck tour, you ride along the road, then roll down a ramp into a lake with a big splash, and the bus carries on across the water as a boat. Most run only from spring to autumn, and strong wind or high water can cancel a trip, so check the season and book ahead.
The KABA bus rolls down a ramp into Lake Yamanaka, the largest of the Fuji Five Lakes, and cruises the water with Mount Fuji rising ahead on a clear day. Unlike most duck tours it runs all year, though wind, fog, snow or high water can cancel trips, and booking ahead is recommended. Lake Yamanaka is a little over 2 hours from Shinjuku by highway bus.
Starting from the michi-no-eki, a roadside rest stop, in Yunishigawa, deep in the mountains of Nikko in Tochigi, the bus drives straight into the lake behind Yunishigawa Dam. Besides cruising the lake, the tour visits dam facilities that are normally closed to the public. It runs from late April to late November.
At a yacht harbor on Lake Suwa in Nagano, the bus splashes into the lake and then tours the water, with the mountains around the basin all around you. It runs from April to the end of September and is closed on Tuesdays and Wednesdays. Lake Suwa is about 2 hours from Shinjuku by limited express train.
From a roadside rest stop in Nishimeya, Aomori, the gateway to the Shirakami Mountains and their World Heritage beech forest, the bus drives up to Tsugaru Dam and splashes into the lake for a cruise of about 20 minutes. It runs from late April to late September and is closed on Wednesdays. Booking ahead online or by phone is recommended.
From a roadside rest stop in Nagai, Yamagata, the bus heads into Lake Hyakushu behind Nagai Dam for about 30 minutes on the water, with views of the Ryujin Bridge across the lake. Tours generally need booking, and the season changes from year to year, so check the official dates before you go.