During Songkran, Phuket centers on Patong's beach road area, and this guide splits the day into morning, midday and afternoon around that. April daytime reaches 35-40 degrees, so sea trips that start early tire you less.
Morning options are the Maiton and Khai ice-cream yacht (07:00-08:00 pickup), the Raya water-slide catamaran (07:20 pickup) and the private yacht's 07:30 slot. The first two return at 13:00 and 17:00 respectively, so choose to match your afternoon.
Midday suits activities in Patong itself. Surf House is open 09:30 to midnight, Erawan zipline runs 08:00-18:00, and Pum Thai's 45-minute course gives a rest after getting wet.
Afternoon departures run into sunset. The sunset yacht picks up at 13:00 and reaches Chalong at 18:00; the Yanui Beach tour picks up at 12:40 and ends at 18:00. Both overlap the evening water-fight hours, so check the return time.
Sea tours carry minimum numbers: the sunset yacht, Yanui and the Raya water-slide trip each need four guests and can be cancelled if short. Many of these tours exclude infants, pregnant guests and the elderly.
Roads can slow during the festival, so allow slack around pickup times and wait in the hotel lobby. Hotels in outlying areas may be out of pickup range or carry a surcharge, so confirm on the listing.