Collect the indicated number of hidden seashells to unlock the corresponding day.

Day	How to unlock
Day 22 (Private Helicopter Tour)	8 Seashells.
Day 23 (Snorkling Trip)	15 Seashells.
Day 24 (Off Road Tour)	25 Seashells.
Day 25 (Adventure Rafting)	35 Seashells.
Day 26 (Bike Excursion)	45 Seashells.
Day 27 (Submarine Sightseeing)	55 Seashells.
Day 28 (Private Jet)	63 Seashells.