If you're looking to explore more of your island in Animal Crossing: New Horizons, then you're going to need to know how to cross the river! There's a lot more to explore in the game, and you've got quite a large area to build upon. Let's take a look at what you need to do to access more of it!
How to Get Across the River
Getting across the river isn't too hard, you just need the right tool for the job! The tool required is the Vaulting Pole, which can be obtained on the second full day on the island! First, you are going to want to run through the basic tutorial of the game. This is pretty much an hour or so of playing through the game and following orders. Once you've free and on your own, you will want to get yourself at the very least a Bug Net or a Fishing Pole. These are pretty easy to get, just grab some branches off the ground and then craft them at the crafting table. You can find this in the green tent that houses Tom Nook.
Now, you need to catch five different bugs or fish! It doesn't matter which of these you find, but they have to be five unique ones. So, catching a mix of both bugs and fish will likely be easier! If it's night time, I found that fish were a lot easier. Bugs are harder to find, but there's usually a Moth flying around outside of Nook's tent. Be careful for the spiders though, they will lunge at you if you're not careful! Once you have your five unique items, you need to bring them back to the green tent and hand them off to Tom Nook!
Tom Nook will be so enamored with these items that he will call up a friend of his! This friend is Blathers, who is an owl that runs the museum. You will need to place down Blathers' tent, which will eventually become the museum. So, make sure you're serious about the location you pick! Once you place the tent, Blathers will be inbound to the location, but will not arrive immediately. You will need to wait a full day to return back to the tent and interact with them.
After you've waited a day, you can go back to the tent and talk to Blathers. He will give you the DIY plans you need to create a vaulting pole (you'll also get plans for the shovel)! Once you've got that, read the plans and head over to the crafting table. The first vaulting pole you get access to will cost you 5 softwood to craft, so make sure to have that beforehand (just chop some trees). And that's everything! You should now be able to craft a vaulting pole and get across the river in Animal Crossing: New Horizons!