It is dangerous to land your boat in the swamp because there are creatures there that are uniquely suited to wrecking your boat, and you, as soon as you get there. We always tell people to look for a swamp that has a meadows or black forest next to it.

However, after looking at a few maps on the map website, many of the good swamps either spawn on their own islands, or next to the plains. You might not always be able to do it the recommended way. If you can see the plains from where you are standing, or can see the border of it clearly on your minimap, there's a reasonable chance that something in there will come in while chasing something else.

It can be done but you really need to know what you are doing. In other words, yes it's dangerous. If you have no choice, you could build an outpost up in one of those indestructible trees, provided that you survive the initial landing. Make sure it's fully covered and don't go out at night, unless you like wraiths. Make sure it isn't close to any ruins or standing stones, because those often have spawners, which could spawn archers.

I'd say practice on a little strip swamp until you have some idea what you are doing, and look for turnips and other resources while you are there. Or maybe you'll find a better alternative, so keep looking.