Heidi Klum rescues one of her family's nannies from a riptide in Hawaii
04/03/2013 AT 11:20 AM EDT
When Heidi Klum saved her 7-year-old son
and two nannies from the strong undertow of the Pacific Ocean on her Hawaiian vacation, she says she was just doing her duty as a mother.
"People are used to seeing me on the beach in a bikini, smiling with the wind in my hair," Klum, 39, tells PEOPLE exclusively of the scary scene, in which her son Henry and two nannies began to struggle in the powerful ocean current.
"These photos taken recently look much worse that it really was that day. I did what any mother would do," Klum, who jumped into action with boyfriend Martin Kirsten
, says. "Henry swam out of it. I grabbed him at the shore. The nannies were the ones in much deeper trouble."
Continues Klum: "Never
underestimate the power of the ocean."
A friend adds that the family was surprised they "were being photographed and no one would come help."
After the frightening incident, Klum and her family arrived home safely in Los Angeles