Jiraiya straightened himself out quickly enough and went about the business of sorting out just whom had ruined his day.
First off, he concluded that it was unconscious, whatever it was. He observed it for ten full minutes to be sure of this. Caution was the greater part of valor, and all that. Actually, he was trying to discover what the hell it was so he could figure out the best way to get back at it. Eventually he got up the nerve to get closer. It was warm to the touch, probably from the glaring late afternoon sun, and smooth. Metallic. So whatever it was wore armor.
It was then that he caught another splash and glimmer of blue-green scales. They weren't all dead! His joy and his energy renewed just as suddenly as they'd been sapped, he practically bounded around the hulk of metal and into the murky surf, giant armor-wearing party-crasher temporarily forgotten.
"Oh, mermaidens! Please come out! I had absolutely nothing to do with this rude intrusion! I came with the intention of watch... I mean, listening to your lovely voices!"