WHAT COULD HAPPEN IF IM OUT IN THE SUN FOR 10 HOURS WITH NO SUNBLOCK?

im on vacation with my family and i was at a theme park with no sunblock for about 10 hours straight. now this is in 100 degree weather (possibly more) and on top of that. i was out the next day for about 6 hrs without sunblock on. :/ and today when i was at the zoo (4hrs) my skin started to hurt really bad. and tomorrow im going to be out again (possibly 4-5 hrs) and i was wondering what could happen if i don't wear sunblock?