Is it ok to go swimming and lay in the sun after acupuncture and cupping?

Generally Yes: In most cases i see no problems with swimming and laying in the sun after acupuncture and cupping, but it seems reasonable for you to ask the practitioner who is performing these procedures. In some cases they might have a reason to advise against it (depending on the reason for your treatment), but i believe it would almost always be ok- unless they want you to avoid exertion or becoming heated.

Wait at least 4 hrs: After cupping and acupuncture, i recommend that my patients not engage in any strenous activity for that day (some acupuncturists recommend as little as four hours prior to excercise). If the person was to lie in the sun, they would need to ensure that they did not burn.