I was wondering if there is a word that describes a piece of land that is being surrounded by river(s)?
Is "island" appropriate for this? I always thought the word Island means a piece of land surrounded by a large amount of water that you need some kind of naval transportation to get to.
In this case, you can possibly just swim over or build a simple bridge and you can get to the center piece of land.
Per the OED, an eyot or ait is
An islet or small isle; especially one in a river, as the aits or eyots of the Thames.
An small island in a estuary, lake, or river is a holm
Holm An island in a river.
This is an island.
A large example of such an island was the "Île-de-France". Prior to the French Revolution, this region of France was almost completely bounded by rivers.
The Île-de-France was an extremely large example of such an island. Most such islands are in river deltas, and are much smaller.
As Peter Shor pointed out in the comments, "Manhattan Island is such an island. It's a little over 2 miles wide, and it's bounded by the Hudson River, the Harlem River, and the East River, all less than a mile wide (sometimes much less). And there are indeed bridges (over a dozen of them) to Manhattan from the east, west, and north."
It's pretty common for there to be landmasses in rivers. One of the most (in)famous is Three Mile Island on the Susquehanna River in Pennsylvania, known for being the location of a partial nuclear meltdown in 1979. Here are all the named landmasses (according to Google Maps) between Three Mile Island and the Market St Bridge (to the north):
My point is that in practice these landmasses are almost always called "islands." If you need more examples, you can also look at the Potomac going northwards from DC.
An "islet" is a small island. That may be more appropriate.
Towhead is used commonly in formal American English and "Isle" or "Islet" in casual.
