Several possible Animal Crossing: New Horizons features and updates have been data mined by Twitter use Ninji (as spotted by Nintendo Everything), including fan-favorites such as diving, as well as increased farming options, two Museum upgrades, and more.
According to Ninji's findings, diving in New Horizons will work much like it did in previous games. You'll be able to grab plenty of new fish, as well as seaweed which may be used for new crafting recipes. Relatedly, there's reportedly a "Seafood" Critterpedia entry with 33 slots, 32 of them currently empty. If diving is indeed a thing, it may be connected to an extra dock on the north end of the island.
Two more returning features were also spotted in the game's backend: fake art and, more importantly, bushes. Ninji turned up entries for azalea, hibiscus, holly, hydrangea, camellia, and osmanthus bushes, so your garden may get some colorful new additions soon. Speaking of which, your fields may be getting some new options as well, with tomatoes, wheat, sugar cane, potatoes, carrots, and pumpkins appearing in the data.
A lot of these look and sound pretty credible, but as is always the case with datamined information, there's no guarantee that any of these features will make it to the live game. And even if they do, there's no telling when they'll arrive. Ninji speculates that some features will be added in the coming Earth Day update, but we won't know for sure until the update arrives later this week.