September is the sweet spot.

September. Kids are back in school, so crowds thin out, but the weather and water are still warm enough that all the boat tours are running. You get the best of both worlds without the summer chaos.

May also works if you don’t mind cooler water and the occasional rainy day, but September is more reliable. October starts getting iffy—some operators shut down early if demand drops or weather turns.

Just check local tour schedules a week before you go. One random closure can ruin the whole point.