Boat tours are genuinely weather-dependent, and knowing how operators typically handle cancellations avoids unpleasant surprises.
What triggers a cancellation or reroute
Rough seas, official park closures (as with the Similan Islands' seasonal closure), and occasionally low visibility all lead reputable operators to cancel or substitute an itinerary — a genuine safety decision rather than an inconvenience imposed carelessly.
What "rerouted" usually means
Rather than a flat cancellation, many operators substitute a calmer-water alternative destination on a rough-sea day — worth asking specifically what the substitute would be when booking during green season, so you know what you're actually paying for if conditions turn.
Refund and rescheduling policies
Reputable operators generally offer a full refund or free rescheduling for weather-related cancellations they initiate — this is different from a customer-initiated cancellation, which typically follows a stricter, time-based refund policy. Confirm which policy applies to a weather cancellation specifically before booking.
Booking with this in mind
During green season, booking a tour earlier in your trip rather than on your final day gives you a chance to rebook if the first attempt is cancelled — a simple scheduling choice that avoids losing the activity entirely.