Deep lake
A lake whose bottom cannot be seen — calm surface holding an unknown depth underneath.
A deep lake in a dream is the dream's image of a calm surface holding an unknown depth underneath. The surface tells you nothing about what is below; the depth is real and unmeasured. The dream brings the deep lake when something in your life — a quiet person, an institution, an old friendship — is calm at the surface and is carrying much more underneath than the surface shows. A deep lake swum across with respect is the dream affirming the appropriate care. A deep lake dived into for show, with no sense of the depth, is the dream noting that you have treated the unknown depth as if it were transparent, and what is down there will decide the next part of the meeting.