This page will hopefully serve as a guide to help undergraduates find research opportunities during the summer as of Jan 2026:
1) Official Programs: Most of these official programs run fairly similarly, just different funding sources. They are approximately 8 to 10 week summer programs at various U.S. universities/laboratories across the country or internationally that provide about $5,000 stipend/salary (give or take) and most either provide housing/meals or an additional housing stipend as well as covering travel cost. Most require Resume/CV, a personal statement/research statement, and 2 letters of recommendation preferably from one of your professors
The NSF REU - by far the most popular and known about with the most options
Here's a link to the official NSF REU website: https://www.nsf.gov/funding/initiatives/reu/students
They have a link on that site for a Directory of REU Sites. This directory lets you search by location or Research Area. It is usually a bit out of date with several sites listed that no longer have active programs and a lot of dead links. I'd use this as a guide, and if the link doesn't work for a program you're interested in, do a quick Google for "Whatever University" REU 2026. Some of these still have active programs, but just never updated the link to the program's new website. I was curious how many sites were still active so did a quick search for the "Chemistry" Research Area and looked for environmentally relevant programs and found the links listed below as potential options you might be interested in. The applications seem open already with deadlines in mid Jan to late Feb. I would also recommend checking the Earth & Environment Research Area, though in my experience Chemistry has more and better funding. There may be more local options if you are interested in the materials research side of chemistry which can still have environmental implications/applications.
Links:
https://www.chem.colostate.edu/summer-program/summer-programs/
Https://www.hws.edu/academics/microplastic-reu/application.aspx
Https://www.chemistry.msstate.edu/academics/undergraduate/reu
https://sites.google.com/sdsmt.edu/bace/home?authuser=0
https://www.biosphere2.org/education/university-programs/research-experiences-undergrads-reu
Https://artsci.tamu.edu/chemistry/academics/reu.html
International summer research opportunities: These are a super cool opportunity to get paid to live abroad for a summer. NSF has a few listed in their Directory of REU sites, but I think some of them are unfortunately no longer funded. The University of Florida one is still running (https://reu.chem.ufl.edu/program-application/), and you might be able to find others still operating if you look down the directory list. Other things might pop up as well if you just google international/abroad research opportunities. There's a good program called DAAD (https://www.daad.de/rise/en/) that has some research opportunities in Germany though this one has an early fall deadline. DAAD also has a RISE Professional program for post-baccalaureate. These are super competitive programs, but I do encourage you to apply if you are interested even if you feel like you don't check all the applicant boxes for "encouraged." You really never know who they might pick in these things, though you definitely won't get it if you don't try.
Department of Energy sponsored summer research internships: These are cool because you could end up at one of the DOE National Laboratories (including Savannah River National Laboratory if you wanted to stay closer to home, but the other national labs are a lot cooler). National labs have some of the coolest instruments and interesting research projects, and you would get to work with one of their scientists (hopefully a good mentor and impressive reference for future applications). It's not uncommon for this to lead to a potential job opportunity after you graduate as well. I didn't look into the fine print on these but the link below has a list of different opportunities that you could look into more closely.
https://orise.orau.gov/internships-fellowships/undergraduates.html
HHMI: This one is traditionally a bit more health focused, but the one I received let me study the sorption of pesticides to soil organic matter at LSU for a summer, so it might be worth looking into more closely: https://www.hhmi.org/programs/cech-fellows
Do a Google search for what you are interested in. The ones above are the ones I know about, but I'm sure there's more out there. You'd be surprised what you can find now that you know these kinds of opportunities exist
2) Professor based research: most professors, myself included, do not mind taking on an undergraduate student for the summer if we have the funding to pay them. I recommend looking outside of your own institution, but if you want to stay for the summer, you could ask your professors if they have an opportunity, or know of a friend or collaborator at another university, who could take you on for the summer to do research. Alternatively, you could find a local university and email a professor whose research interest align with yours.