A short walk past Glanni waterfall is a secluded little glen with a tiny waterfall, pool, and lovely moss-covered stream.  The river flows from under the lava here, and there is a well-maintained path and staircase down into the glen. Part of the grass is roped off (likely to try to protect it from foot traffic), but picnicking here would be easy.

There is a small coffeeshop (open summers) in the small parking lot.  Glanni and Paradise Hollow are about 30km north of Borganes, just off route 1 and near the small town of Bifrost.  At the site, the signage is a little vague: take the walking path to the right to see the waterfall and then further on to the glen.