Hi! I went through Traceys' site (above) to Aisling dream interpretation.
found the following:


"Water symbols i.e. sea, rivers, lakes, canals, etc. reflect the spiritual or cultural life of the dreamer. How water appears or is organized indicates the dreamer's philosophy of life. A river indicates the dreamer needs a more free spiritual flow. A canal or swimming pool, both man made structures, indicates man-made or conventional ideals are restricting the dreamer's Spiritual flow. A lake or pool indicates that the dreamer does not have a spiritual outlet. The sea or ocean indicates the dreamer's spirituality / life is the subject matter. Diving into the any body of water is a request for the dreamer to get into life.

The state of the water can also indicate the condition of the dreamer's blood. Polluted water indicates a need to cleanse the blood by a change of diet and/or improved elimination"


To me the symbols in your dream indicate you may have an aversion to "religion", but
this may be a projection on my part as most have too many restricting beliefs for me.
Water also represents an emotional aspect. Getting in the swim would be getting in
contact with this side of your nature.

Hope this helps.
Margie

Water represent emotions, If the water flows, emotions flow. If you are covered by water it means your emotions are out of proportion. Dirty water means emotions are not flowing you are kind os stuck as the water.
Just my sense of it