A swim ring is read as support that keeps you afloat when you cannot quite manage alone. It may point to a person or a habit you lean on, and to the wish to feel safe in deep water.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.