There's always someone looking for interns.
My recommendation is to ask researchers that work in fields that interest you if they are able to supervise a research project over the summer. I would recommend you prepare a nice CV that you can attached to your email, so that they don't have to ask you for it and delay the process un-necessarily.
I would also recommend to check their websites, since many of them say explicitly "not currently taking research interns" and therefore if you do email them anyway, they might get annoyed and it could hurt your chances of working with them in the future (it probably won't harm you, but in some cases it can, so it's better not to risk it).
If you need help choosing a supervisor, you might ask friends if they have recommendations, or you can browse university websites after clicking on the department you're interested in, and finding the "department members" page.
If you are really keen and have the time, I might recommend to browse some of their papers, for example on Google Scholar or from the publication list on their website. They will be impressed if your email indicates that you know at least something about what they do, and is not just a generic request to work with someone about whom they have not the slightest clue.
Last of all, good luck with your search for an internship!