Help me (girls please)?

Ok i got my period 2 days ago and its kinda sorta slowing down and tommrow im going to one of my friends swimming party and i REALLY wanna swim and get my tan on but i dont wanna wear a tampon cause i have never worn one before and i kinda think its painful but i dont wanna wear one and i dont know what to do cause i heard your period flow stops when your under water but im thinking "whats gonna happen when i wanna come out to tan or something?" can you please help me on what to do?

Thanks