What do these repetitive dreams mean?

I always have these dreams where I am at the beach and all is well, usually with family or friends. Then suddenly, the waves start to get powerful when I am on the shore. Sometimes I play the game where you run up to the waves but then quickly run away before you can get wet. the dream i had last night I was picking up pippies (shells) when the waves would breathe in and leave all the shells on the wet sand. I was doing this with a girl acquaintance who I rarely see. Other times I will just be swimming and then the waves get bigger and bigger and then i try to escape the ocean, but when i finally get on to the shore and am running for the dunes, the waves exhale after breathing in which crashes on me and sweeps me back in to the ocean where the dunes seem so far away, I am often surrounded by sharks and stingrays, and all other scary sea creatures when I am in the ocean. Last night, I got caught in a rip, and every time I escaped the wave, it came and got me again. I was electrocuted by an electric eel when i was being dragged out to see and it felt so real. The dunes, when i can get to them are often like cliffs and as i try to climb them, they just collapse from the lose sand. I have had this dream at least 15 times, it varies slightly but is always the same feeling and atmosphere where i feel so helpless and terrified. I do not consider myself to have any phobias with the ocean and love the beach, but this dream scares me so much. Does anyone know what this could mean or represent.