“The Bathing was so delightful this morning & Molly so pressing with me to enjoy myself that I believe I staid in rather too long, as since the middle of the day I have felt unreasonably tired. I shall be more careful another time, & shall not bathe tomorrow, as I had before intended.”
letter to Cassandra, from Lyme
September 14, 1804 
I love that feeling of having swum in the ocean for too long. I always wondered what a bathing machine was, which Jane would have used when she swam. It sounds like quite a contraption, but actually it was just a little cart to keep people from seeing you in your bathing clothes. More info on Wikipedia.