Mermaid

You were surfing on one of the deserted beaches. The weather was cloudy and the waves were frequent. You sailed away from the shore for a decent distance, waiting for the next wave to appear. You were lying on the board and looking deep into the water, noticing some kind of muddy movement below. You tensed up, but you kept peering, trying to figure out who or what was floating there. A big fish? It doesn't look like it... But a person could hardly be there either. You felt insecure and afraid of the unknown and turned around, assessing the distance to the shore. You can't get there fast.