Agatsuma Gorge is a good place to check on your way to Kusatsu Onsen. It is situated right after Higashiagatsumamachi and before Naganohara. The gorge offers beautiful scenery: river, waterfalls, and mountains. It is a great place to admire fall colors for example or the cherry blossoms during spring. There is a trail that takes 25 minutes one way, and follows the Agatsuma River.
Due to a big construction site for a new dam, one way of approach is closed. You will be redirected to another road from where you can access the tourist attraction. There is free parking at Junisawa Parking Lot, some facilities and the Sarubashi bridge that opened in March 2017. I went there a couple of times this year just for a small walk.Usually, there is nobody around, and thanks to the closed road, it is very quiet.
If you catch a train to Tsumagoi (Agatsuma line from Takasaki), you will also be able to enjoy a nice view over the gorge.
Getting there
Between Kusatsu and Shibukawa, road 145 or 375.