"When she (Wendy) stole softly to the edge of the lagoon she might see them by the score, especially on Marooners' Rock, where they loved to bask, combing out their hair in a lazy way that quite irritated her; or she might even swim, on tiptoe as it were, to within a yard of them, but then they saw her and dived, probably splashing her with their tails, not by accident, but intentionally." Peter Pan by J.M. Barrie, Chapter 8 The Mermaid's Lagoon.
The Little Mermaids enjoy their shell lagoon, they never get bored with brushing their hair and sharing abit of sea-side gossip. and, why should they? After all, the water's the perfect temperature.