While we've sent spacecraft to all the planets in our solar system, there are a few dwarf planets that haven't been visited:

* Pluto: Though the New Horizons mission flew past Pluto in 2015, it didn't orbit it. This means we haven't had a chance to study it in detail yet.

* Eris: This dwarf planet, even larger than Pluto, is located in the Kuiper Belt. No spacecraft has even come close to it.

* Makemake: Another Kuiper Belt resident, Makemake is a bit smaller than Pluto. We have limited information thanks to ground-based telescopes, but no close-up exploration.

* Haumea: This egg-shaped dwarf planet is also in the Kuiper Belt. Like the others, it remains a mystery to us without an up-close look.

Other bodies in the solar system that haven't been visited:

* Many asteroids and comets: We've visited a few asteroids, but there are millions out there!

It's important to note that "visited" can mean different things. A flyby, like with Pluto, is a visit but provides limited data. An orbiter, like around Mars, allows for more in-depth study. And a lander, like on the Moon, allows for surface exploration.

The future holds exciting possibilities for exploring these unvisited worlds!