More than 100 people attended his funeral on Thursday, paying tribute to "the most caring man in the world" and a "doting father".
Cousin Sharon Moana Hei said Jondahl had been at the beach with his friends from church.
"I believe he was out on a jetski and his heart must have just stopped.
"There was no warning and you would think he was physically fit when you look at him.
"The family are absolutely devastated but they are very close and will come together to help each other through this difficult time.
"The service was a celebration of who he was as a person. He had a huge heart and had so much compassion and time for other people.
"He will be sorely missed by everyone. It's heart-wrenching that a man with such a bright future has been taken from us."
In January last year, Jondahl was on a farm in remote Parakao, 45km west of Whangarei, and had just finished getting dressed for his wedding, when he fell over.
He had been diagnosed with a heart condition but had never collapsed before.
Family and friends watched as Jondahl, who was lying down, exchanged vows with his sweetheart in a shortened ceremony.
The bride went to hospital in her wedding gown and their honeymoon was spent in the coronary care unit.
The couple enjoyed married life for one year and recently welcomed a baby girl, Aroha, meaning love.
Hei said that Jondahl was infatuated with his daughter and was incredibly happy being a husband.
"You couldn't have found a happier couple. They just treasured every moment together.
"Aroha looks just like her dad, she has his big beautiful eyes.
"He was so proud of her, doting on her all the time. It is incredibly sad that he doesn't get to hold his daughter any more.
"Her wedding, first day at school - he will miss out on all of these things."
The Jondahls had hoped to renew their vows and experience the wedding and honeymoon they had both dreamed of later this year.
Speaking in February last year from their home, Tanya Jondahl said that nothing was going to get in the way of the pair becoming man and wife.
"People were saying, 'It will be all right. We'll do it another day. We'll come back.
"[But] In our heads, this was our wedding day for months and months and the celebrant was there and everyone was there, so why not?
"The celebrant just made sure we said the bit that you have to say to legally get married.
"That's the main thing for us, that we got married and we're together."
