In the silverware drawer. This according to a houseboat rental operator after one of my lost weeks on a Minnesota border lake. He figured people took off their watches to swim, then became so liberated from responsibility and routine that by the end of a week, they completely forgot about watches. All watches, and other left-behinds, are sent to the owners, of course. I hope to add Wisconsin, Iowa, and the southeast to my escape list as soon as possible.
Houseboats are big and slow.
Ten miles per hour is an average cruising speed. Without an expensive tracking satellite system, there is no TV on most lakes. Even radio is marginal in the more remote areas. The number-one priority might be nothing. Nothing except watch scenic shorelines slide slowly by, catch up on a good book, answer overdue letters, and soak up sun.