At Oahu's North Shore, captain Sonny Jennings and his core team of lifeguards monitor the dangerous Hawaiian waters. Meanwhile, the new lifeguard recruits compete to join Sonny's district. Between diving headfirst into difficult and life-threatening conditions to rescuing injured and in need of help beachgoers and surfers, the lifeguards are also dealing with their own personal issues.

When a flash flood sweeps a young tourist away from her family and out to deep sea, Sonny, Em, and Will race into action to save her. Going against Sonny’s wishes, Em takes a bold risk and places her own life in danger in hopes of rescuing the lost-at-sea tourist. Meanwhile, Laka supervises rookies Kainalu and Hina’s first day on the job.

Em works to earn the team’s respect when she is left in charge and Hina and Kainalu juggle multiple beachside emergencies. Meanwhile, Will’s fiancé pays him a visit at work, Sonny opens up to a former lifeguard about his trauma since losing his nephew, and Laka continues his flirtation with EMT Jenn.

A morning hangout on the beach almost turns deadly for a group of college kids when two of them get trapped in a collapsed sandpit. Meanwhile at sea, Sonny, Will, and Laka race to rescue people stranded after a shark attack. During a rescue, Em catches the attention of Fire Captain Sean Harimoto, and Will learns if he made the cut for the firefighter job he has been pursuing. Hina makes a move with Kainalu, and Sonny attends Zion’s memorial fundraiser and attempts to reconnect with his sister for the first time since the funeral

The lifeguards of the North Shore experience the most dangerous ocean conditions the district has seen in years. Sonny assigns Laka as acting lieutenant as Em has the day off and joins Jenn to catch some massive waves. Meanwhile, Kainalu's father pressures him to leave his shift and help him with his campaign over patrolling the beaches. Hina thinks she is ready to back-up the rescue skis, and Laka and Will almost make it through the day when a fight breaks out among locals. Emotions reach a boiling point for Sonny when he experiences another loss.

The North Shore community comes together for Rocky's paddle out. Hina thinks about switching districts. Laka, Will and Kainalu try to save a beachgoer that accidentally speared his own foot. Romance heats up between Sean and Em.

An influencer gets swept into the ocean while trying to film a new video; Kainalu and Hina discuss setting boundaries within their home; Mayor Emerson makes good on his word with Captain Sonny; Jenn finally agrees to go on a date with Laka.

Sonny, Em, Will and Laka look for missing paragliders that were pushed into the ocean by a down draft; Kainalu invites Hina to a party with his ex-girlfriend; Jenn doesn't think Laka is serious enough for her; Sonny puts in his notice to retire.

Christmas cheer is in the air as the lifeguards prepare for their annual holiday toy drive; while surfing, a local grandpa has a heart attack and is rushed to the hospital; Sonny tells Laka he is not ready to become a lieutenant.

The team races to the rescue in the aftermath of an ATV accident; romantic tensions are high between Em and Will as well as Kainalu and Hina.

Em and Will's relationship struggles as they navigate the return of his fiancée. Kainalu asks Laka for help. The team races to the rescue when a group of locals are involved in a serious accident while riding an inflatable Supsquatch.

The team is on high-alert when a tsunami advisory is sent out following a powerful earthquake.

Captain Sonny and the Ocean Safety team face their most dangerous rescue yet when a literal minefield is discovered on the ocean floor. Meanwhile, on the beach, a hugely popular influencer will do anything to capture viral content for her massive following.

The team races to rescue unresponsive cliff jumpers; Hina tries to navigate family issues; Will and Em hope to get over each other by rebounding with other people.

The team searches for two missing teenagers; Will does not get along with District 7's new team member; Em receives a surprise visit from her estranged mother.

Em takes the day off to spend time with her mom, but races into action when she comes across an unresponsive cave diver; Will confides in Vince about his personal anger issues; Laka searches for a missing local.

Will and Em race to rescue a windsurfer that wipes out and suffers cardiac arrest; Capt. Sonny reunites with Ocean over a family lunch and Em realizes her mom is back to her old ways; Hina tries to hide her jealousy over Kainalu's new relationship.

While monitoring the beach, Laka and Will notice a toxic smell coming from a van and discover a kid unconscious and surrounded by drug paraphernalia; Em befriends a disabled veteran; Hina finally confesses her feelings to Kainalu.

Hina and Kainalu assist the U.S. Coast Guard in searching for two missing snorkelers left behind in the middle of the ocean; Sonny takes matters into his own hands about Vince; Em receives a job offer from a very rich person.