Shiga Prefecture is a great place to visit because it is located next to Kyoto and you can experience a rural life here. If you want to enjoy the Japanese countryside while visiting famous touristic cities like Kyoto or Osaka, it is the best option: It takes only one hour from Osaka and 30 minutes from Kyoto.
Apart from experiencing the rural lifestyle such as visiting rice fields, tasting Sake at Sake breweries, or, making tofu, you can enjoy outdoor sports in Shiga.
You can do a lot of cycling here: You can cycle along rice fields, you can cycle in the forests, and you can do Biwaichi, to cycle around Lake Biwa which is the biggest lake in Japan.
You can do a lot of mountain climbing, rock climbing, trekking, and walking: There are many mountains to climb in Suzuka mountain range; there are quite a few secret rock climbing spots; and there are a plenty of places to go for walks such as walking along rice fields, walking in the forests, walking along rivers and lakes, and walking through little country villages.
You can enjoy most marine sports at Lake Biwa such as canoeing, wind surfing, boating, and sailing.
I sometimes take my son to Notogawa Suisha and ride a canoe there.