Usually students doing a summer internship for credit are required to pay college tuition which could leave them incurring some debt over the course of summer break if their internship is unpaid. Each student is different and I recommend that students totally evaluate their individual circumstance prior to making a decision. If a student does not need the credit to add to their college transcript, my recommendation would be to not do the internship for credit and perhaps wait and do one for credit during the fall or spring semester.
Even without receiving credit, the internship will still provide an opportunity to gain the relevant knowledge and skills required in the field as well as add an important element to the resume. Gaining relevant experience through internships, co ops, service learning, or externships and making professional contacts while there are two of the best things a student can do to prepare themselves for getting a job in their field after college.