龍潭湖風景區 has a pretty cool English translation: The Scenic Area of the Dragon Pond (even though from locals I’ve been told it should be more similar to “Water Dragon Lake”, but as it often happens the literal translation is not necessarily correct).
The location is just a hair north of Yilan. On sunny weekends the lake is crowded, but the main attraction is not the lake itself. Not long ago a popular TV show was recorded there, and at the coffee shop/restaurant/bar it’s still possible to recreate the same scenes from the movie. I’m not much into TV shows, left alone Taiwanese TV shows, but a lot of people enjoy going there and spend a bit of time at a ‘popular” location. The lake itself is not bad, but it’s pretty small and there’s not much to do apart from having a walk around.
If you’re looking for a nice lake, then Plum Blossom Lake is a much more attractive location, but if you’re travelling north of Yilan city and you want to have a break by the lake, then the Water Dragon Lake Pond (whatever) is a nice stop.