Budget two hours door to door for a 90-minute cruise, plus parking and check-in. Longer trips that push north into Port Royal Sound run closer to two and a half.
The morning departures are the reliable ones. Water is flattest before the sea breeze fills in, the light is good for photographs, the heat is manageable, and anyone prone to motion sickness will have a much better time. From late June through August, thunderstorms build over the mainland through the afternoon and can cancel a mid-afternoon trip on short notice.
Late-day trips trade calm for light. The marsh goes gold about an hour before sunset and the sounds turn to glass on a still evening, which is why the dolphin-and-sunset combination sells so well. Just know that sunset here swings by three hours across the year: near 8:30pm at the end of June, closer to 5:20pm around the winter solstice. Departure times shift with it, so a "sunset cruise" in October boards in broad daylight in early evening.
Tide matters more than most visitors expect, with a six to nine foot swing depending on the moon. Captains schedule around it because a falling tide pulls bait out of the grass and dead low can shut the shallower creeks to anything with a propeller. Winter is quiet, the water sits in the fifties, fewer boats run, and the dolphins are still here.