Lake or Marsh means ‘open’ or ‘loose’. It can be literal: the cart losing its axle strap. As part of a hexagram it means opening up to others, to exchange, to interact, to relax together. As ‘marsh’ it is the breeding ground for all species, for all connections, for love and hate, joy and disappointment, for storytelling and magic.
When Lake is above or outside, the lower trigram expresses itself in accord with the properties of Lake. Or your surroundings demand it. The situation has everything to do with other people or your station in society. Your connection to them or the lack of it. Are they friends or helpers, or the opposite, oppressing you? Do you have to navigate through this with care and responsibility or can you enjoy yourself in easy company?
An outer excess of Lake can cause (a feeling of) being oppressed by others, or blindly accepting the mores of the world around you.