You can unlock the Beach at level 12. When you reach this level, the "Restore the Beach" task appears. Once you complete this task, the vacationer Kamehame starts coming to the Beach on his jet ski. When you reach level 19, Penny joins him.
In one visit, you can fulfill 3 orders for Kamehame (1 order per hour) and 5 orders for Penny (1 order per hour).
You receive a small reward for fulfilling each part of the order. When you fulfill the final order in the chain (the third for Kamehame and the fifth for Penny), you get a final bonus reward.
After receiving a reward for one task in the chain, you have three hours to collect resources and fulfill the next one. If you don't manage to fulfil the order in time, the task chain is interrupted and the vacationer sails away. If this happens, you cannot get the final reward.
When you complete the task chain, Kamehame and Penny sail away and return after 3 hours. You can also use Gems to speed up their return.