Crafting is a key tenet in Disney Dreamlight Valley, and to create items such as fiber and rope you'll need an unusual component: seaweed. As part of the quest to fix Moana's boat, you'll find some seaweed initially, but after that, it doesn't seem to spawn on the beaches. Worry not, Valley dwellers, as there is a tedious but surefire way to farm seaweed, so let me kelp you with that.
Disney Dreamlight Valley: where to find seaweed
First things first, you'll need your fishing rod and a stack of fruit or meals to replenish your energy. You'll also want to pair up with a character who gives a fishing bonus—hopefully, you've chosen someone other than Goofy—as you'll get extra materials or fish, then head down to Dazzle Beach. It would also be a good idea to go into the Furniture screen and move Goofy's crafting table down onto the beach to save you time when you're ready to craft all that fiber.
What you need to do is cast your line into the water away from the bubbling circles where fish are caught. Just cast your line anywhere and wait for the prompt to start the catching process. You'll either catch lots of basic fish or seaweed, so just keep fishing and picking up the extra seaweed your companion chucks at you.
You can take seaweed to the crafting bench and make fiber from it which in turn will make rope. You'll need this for Moana, Donald Duck, and Goofy's quests, so get fishing. Seaweed makes five fiber at a time, and you need eight fiber to make rope, so you'll need to get farming asap if you want to power through these friendship quests.