Once you’re ready to depart, make your way to Hau’oli City–specifically the Alola Photo Club. It’s the brand new building between the malasada shop and the police station along the bottom half of the shopping district. It’ll also be marked by a red flag on your Town Map, just in case you’re drawing a complete blank.
Upon stepping inside, the clerk will immediately greet you and persuade you to take a commemorative photograph.
After taking a photograph or otherwise, you’ll be handed the Photo Album for storing photos. Once you’ve had enough fun messing around, leave the photo club. Outside, Hau will come along to greet you, together with his newly evolved starter Pokémon. Kukui and Lillie will also catch up.
The original plan was for the whole group to travel to Akala Island on Kukui’s creaky sailboat, but Hau has other ideas. Instead, he wants you to try some Mantine Surfing at Big Wave Beach. In case you’ve forgotten, it’s the area west from the motel on the lower half of Route 2. When you’re ready to leave the island, approach the Mantine in the sea.
For your first attempt at Mantine Surfing, simply aim to practice the basics. First try to build up good speed by zipping left and right along the waves. You can tell how fast you’re going by the color of the wind around your trainer–it’ll start off white, then yellow and finally red for when you’re going the fastest.
The seas aren’t just your playground though; every now and then, you’ll find various obstacles such as rocks, dozing Tentacools, chasing Sharpedos or even gigantic Wailords. Bumping into these will lower your speed, so watch out. Anyway, try to aim for yellow or red winds around your trainer, before launching yourself into the air.
Once in the air, try testing the limits of how many rolls you can perform at a given height. If you do too many rolls, you may end up landing halfway through a roll and thus miss your landing bonus–and worse of all, you’ll lose all speed gained. Ideally, you want to pull off at least one trick, which is generally 3-4 rolls.
At maximum height, you can pull off at least 7-8 rolls, which is two tricks and maybe an extra roll or two. The key to getting a great score is building up maximum speed, so you can gain maximum height, then pull off as many rolls/tricks as you’re comfortable with, before making a perfect landing. Then repeat.
Anyway, while getting a good score is nice, it’s not terribly important. No matter what you do, you’ll eventually reach the goal and arrive at the next island.