Dreaming and seeing a grotto is explained as the dream with symbolism of deceitful people around the dreamer. This dream means incomplete or false friendships. The grotto also represents unstable rotating circle of unsteady companions.
Dream dictionary: Grotto dream meanings
As caves, grotto has a beneficial interpretation and a therapeutic sense because it represents the bowels of the earth, and contact with the telluric forces.
…To see a grotto in your dreams, is a sign of incomplete and inconstant friendships. Change from comfortable and simple plenty will make showy poverty unbearable….
…To dream of being in a grotto, or cavern in the earth, shows that you will soon meet a near and dear relative: if you live away from home, something will occur to cause your return: such a dream always foretells meeting your absent friends. Lucky lottery dream numbers – 49, 2….
A short journey by water.
…(See Grotto.)…
…All grotto caves have a divining or therapeutic sense. It is a very common childhood dream, even in adolescence. What is really important is what happens inside it, which tells us that’s what really mature and firm in us….