Hannah is a high-school senior and aspiring trauma nurse spending her spring break in Mexico with her best friend's family before heading to Linfield University. Her background as a trained lifeguard gives her a highly practical approach to assessing risks and physical danger. A long-standing crush on Jackson makes her emotionally guarded, but she proves deeply resourceful when the group's idyllic vacation turns into a desperate struggle for survival at sea.

Bennett is a wealthy teenager who quickly ingratiates himself with the Cole family during their Puerto Vallarta vacation. He uses his family's money to fund lavish excursions and presents himself as a generous suitor to Emelia. However, his polished exterior hides a deep sense of entitlement. His reckless choices, such as chartering a private boat despite severe weather warnings, place the entire group in immediate jeopardy.

Jackson is a college sophomore studying criminal justice and Emelia's quiet, observant older brother. Reluctantly joining the private sailboat excursion as a chaperone to appease his parents, he serves as a protective figure for both his sister and Hannah. His interest in true crime makes him highly skeptical of Bennett's sudden generosity and smooth demeanor.

Emelia is a vivacious high-school senior preparing for a solo world tour after graduation. Drawn to spontaneity and fun, she quickly falls for Bennett's generous and charming persona. Her highly trusting nature often places her at odds with Hannah's cautious outlook, leaving her vulnerable when the group's vacation takes a dangerous turn.

Mr. Cole is Emelia and Jackson's protective father. Influenced by Bennett's polite demeanor and shared college connections, he allows the teenagers to charter a private boat. He insists on a compromise that requires his son to accompany them as a chaperone.

Mrs. Cole is Emelia and Jackson's mother, enjoying a family vacation in Puerto Vallarta. Though initially cautious about the private boating trip due to prior commitments, she is ultimately swayed by her husband's compromise and Bennett's respectful presentation.

Captain Keith is a local sailor who lives aboard his somewhat neglected sailboat. Motivated by a large cash payout, he agrees to take the teenagers out on the water despite official weather warnings. He prioritizes immediate financial gain over basic safety protocols.