OK. I did the WHOLE lake all the way around (not literally, first counter-clockwise DOWN from the entrance off CA1 -- route 10 from El Congo -- to the water's edge, but did not go in. I then back-tracked clockwise from the Route 10 entrance UP the mountain to the the Cerro Verde park (and also took many treacherous side roads to explore better views). While there are some beautiful views of the lake going down the tortuous drive (and on some of the very rough side roads), most of the views near the bottom are blocked by high walls around private property. Unless you are committed to a dip in the lake, the drive UP to Cerro Verde offers better (albeit more distant) views plus the bonus of the spectacular volcano views (this is the backside of the Volcanos Park) and is a much easier drive.
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