One day, Lugia challenged himself to hold his breath for a full 24 hours. Even for him, that was quite a lofty goal! Unfortunately, it seems he's very much overestimated his breath holding abilities, and his lungs gave up about 13 hours in, instinctually forcing out his spent air in a massive cloud of bubbles. He's not very far underwater, so he'll be fine, but he certainly won't be surfacing with dry lungs.
EDIT: I've recently realized this was mostly traced from official art. Specifically, this: https://archives.bulbagarden.net/wiki/File:249Lugia_XY_... I don't condone doing this, and had I known at the time, I likely wouldn't have posted this.