To write a good 'Sea of Thieves' fanfiction, you should focus on the setting. Describe the choppy seas, the creaking of the ship, and the salty air. Also, add conflict. It could be a rivalry between two pirate crews over a powerful magical artifact. And don't forget about dialogue. Make it authentic, like how pirates would really talk with lots of 'arrrs' and nautical terms.
First, inspect the area carefully for hidden switches or objects. Sometimes, interacting with nearby objects or following a specific sequence of actions can help you progress. Also, keep an eye out for any in-game hints or tips that might pop up.
It's likely about the adventures in the Sea of Thieves world. It might feature pirates, their quests for treasure, battles on the high seas, and the various strange and dangerous creatures that inhabit that world.