You look for spitting water in the sand, which usually indicates a clam is hidden there.
Dig up the 5 parts and return them to Gulliver.
He will mail you treasures from around the world. Some of these items come in different colours (hula doll, nutcracker, horse, hats). After you help him at least 30 times he will eventually reward you with a golden shovel DIY, so you can make one. I’ve helped him a lot more than 30 times, but still waiting for the golden shovel. It is the last golden tool that I need.
All images found online, sorry for the fuzzy images. I have a hard time getting images from my switch to the computer, so I look online for them.
I stitched Gulliver laying on the beach with his phone, part and a hole in the sand.