OKOBOJI, Iowa — Thursday began as a regular day for 17-year-old Calvin Grosvenor of Okoboji, but before sunset, he was being hailed as a hometown hero.

Grosvenor was fishing on the docks at Okoboji Boats, just like he does every day, when his SCUBA diving instructor, Jose Barba, asked him to go for a dive. A diver was in town from Missouri and needed a partner — "The first rule of diving is, never dive alone," Grosvenor explained — so Barba asked if Grosvenor would go with him.

Newly SCUBA-certified as of November, Grosvenor had never been on a dive without an instructor before. He eagerly agreed to accompany the diver, Jesse Fletchall.

The dive was going swimmingly at first, but suddenly Fletchall was thrown into medical distress, suffering a brain embolism and a seizure. Fletchall quickly sank to the bottom of the lake, a depth of about 25 feet in that location.

Grosvenor immediately sprang into action. He swam over to Fletchall and grabbed hold of him, rising to the surface with his fellow diver in tow. While keeping Fletchall's head above water, Grosvenor swam 100 yards to shore.

As he got close, Grosvenor noticed a bystander near the water.

"I yelled, 'Help! He's drowning!'" the teenager recalled. The woman called 9-1-1, and some nearby construction workers helped Grosvenor pull Fletchall onto the dock.

Fletchall was not breathing and had no pulse, so Grosvenor began administering CPR until the ambulance arrived. Fletchall was then taken to Sioux Falls, South Dakota for medical treatment.

Grosvenor knew how to help Fletchall due to his SCUBA diving training — that and instincts, the teen explained.

"You train for these scenarios, even though you hope they never happen," he said.

Although he is not certified in CPR, Grosvenor said he remembered the technique from a field trip his class took to the hospital as freshmen in high school.

"I think I'm going to get certified now," he added.

Grosvenor later learned that Fletchall had only a 5% chance of recovering from the near-drowning, so he was thrilled when Fletchall drove straight back to Okoboji after being released from the hospital.

"It was relieving to see that he had made it," the young diver said, adding that after such an intense experience, he and Fletchall are sure to be lifelong friends.

Fletchall's family also came to Okoboji, wanting to meet Grosvenor and thank him for saving Fletchall's life. As a token of appreciation, Fletchall gave Grosvenor his lucky diving charm.

"It's been with him on every dive he's ever done," Grosvenor explained. "And now it will be with me on every dive."

Fletchall also purchased a new set of SCUBA gear for the teenage diver, just in time for Grosvenor's 18th birthday on Sunday.

Although his first certified dive included a medical emergency, Grosvenor emphasized that SCUBA itself is not dangerous.

"Diving is a really safe sport," he explained. Most diving accidents occur due to inexperience or because a diver attempts a dive that is above their ability level. If all divers stick to what they learned in training, they are likely to be safe, he said — and they might even save a life.