Ha! No, not a sea kayak, but seaworthy to a degree... actually something similar happened to hubby & me years ago, paddling off Bahia Honda in the Florida Keys.
We were in shallow-ish water -- maybe 10 feet deep, paddling parallel to each other, ca 10 feet apart; ca 3:00 pm, a leisurely, easy, recreational paddle on oceanside of the island. Maybe 300 feet from shore if that... paddling sit-on-top kayaks like the one in the video.
Now he's positioned further from shore than I and because of the afternoon light, he can't see into the very clear water like I can. I turn to him and see a very large, very triangular dorsal fin right behind his rudder. I start to say something but I don't want to spook it -- but I have visions of some humorous "Welcome to Key West!" photo postcard... quickly the beast submerges and swims under my boat, where I can see it very clearly: great hammerhead shark, ca 16 feet (same length as our kayaks). It disappears, we decide to just keep paddling, reach the end of the island and turn back without incident. Meanwhile I'm calling my husband "Chum"... After we take out and load up the car, we stop by the ranger station on the way out of Bahia Honda and tell them what we saw. "Were you fishing?" Nope. "Are you sure it was a hammerhead?" Very!... and the ranger gives us an identification card just to be sure, and yes, it was a great hammerhead: a very unique dorsal fin and head shape. "Not a bull shark?" Nope. "Nothing to worry about," the ranger told us. "They hang out at the bridge in deeper water. They eat tarpon and rays, mostly. Can't re really hurt people. Probably attracted to the bubbles your paddles kicked up."
Our big fish tale, but a true one!
2015 Connor spruce/Indian rosewood
1978 Ramirez 1a cedar