She was swimming. She was actually swimming in the Styx. What is wrong with my wife, you don't swim in the Styx. No one has ever swum in the Styx before, though he did have a nice vantage point to see her arse from if he did say so himself, but that was beside the point, she was swimming in the Styx, of all of the weird things he's seen her do, this takes the cake.
"What are you doing?" Tom said loud enough for her to hear
Startled Hermione turned around in the inky black water to see who had come upon her when she saw it was Tom she gave him a loving smile, I'm the only one she looks at with that smile.
"Swimming, I would have thought that was obvious," she replied teasingly.
"Yes, I see that but why are you swimming in the Styx of all places?" he asked baffled.
"Well dear husband, you don't have anything else to swim in," she replied cheekily whilst grinning.
"We have plenty of hot springs." He replied confusedly, Why doesn't she just use the hot springs?
"Yes, but those are just that 'hot', I wanted to swim in something cold, and seeing as the Styx has the coldest water in the Underworld I decided to swim here," she said it condescendingly as though he was a child, him? a child, he was no child, he was the God of the Underworld.
"Alright, I'll leave you to your swimming then," as he said that he started walking away just before he got about three metres away, he turned around again to try and catch a look at her arse before leaving.