Altara re-surfaced to make sure her equipment and clothes were still here, then dived back down.
She had been delighted to find the lake, and had dived in almost immediately. She hadn't even bothered to change in mermaid form yet, perferring to swim in nymph form for a while.
There were even caves down below! She was so excited she could barely contain herself.
In the corner of her eye she thought she saw something, and she immediately charged upwards, just to make sure. She didn't want someone walking off with her backpack, which now contained every single one of her world-possessions except for her under-clothes.