My period is 4 days late. i'm 16 years old. i have to go on a trip where i'll be going scuba diving. is there any way to induce my period?

Yes & no: While we often prescribe progesterone to induce withdrawal bleed, it's typically part of evaluation for amenorrhea or no menses (http://www.fpnotebook.com/gyn/lab/PrgstrnChlngTst.htm). If period is late in someone who is sexually active, then I worry about pregnancy. if taking birth control pills, one can delay menses by starting next month's pack immediately (thus skipping placebo sugar pills).