A beautiful lake near Santa Ana. Very peaceful and quiet with a few hostels and hotels right on the lake and a road that goes around a little more than half of the lake.
I myself visited two different places on a self-planned day trip. At the first stop I saw the lake head-on from a small wooden platform. My second stop was a viewpoint near or at the viewpoint ‘El Gran Mirador 1’. There are various nice viewpoints around the lake, but the bus that goes along the road of the lake does not run super regularly and the distances are a bit far if you are there by foot and only for the day.
Thereore I would consider staying overnight to have a little more time. Because the lake is definitely beautiful.

Go or not? I don’t think the view on the lake from right in front of it is that amazing, but the view from high above was really beautiful 😊 So generally yes, but don’t expect something like Lago Atitlán 😀