Martina Sjöberg was part of the experience on Thursday outside Härmanö head, west of Orust.
They came up with the big dorsal fin and the blowing sound. It was completely incredible. Unforgettable. I'll carry it with me for the rest of my life, she says to the radio.
She reported the incident to Sweden's spade whales, which collects reports on spade whales in Swedish waters. The organization estimates that one of the spade whales was a calf that was max one year old.
It was very fine, says Sjöberg.
She got a little pulse when a lone male came a bit too close and swam under the boat.
Then he turned and swam under us again. He lay on his side and looked up and swam on. Then we were a bit scared, she says to P4.
May is the month when it's most common to see spade whales in Swedish waters, according to Sweden's spade whales.
