>> reporter: david hartley had always been interested in visiting the sunken church in falcon lake. on thursday morning, september 30th, a week before he and his wife would move home to colorado, david decided they would go. did you know then what you must know now, there had been several attacks on that lake? that fishermen don't cross into mexico in that lake anymore. >> we did know that there were attacks. we didn't know where they were exactly. >> reporter: you had no worries whatsoever when you took those jet skis? >> no idea. >> reporter: as tragic as this is, what i think i'm hearing from you is what the hartleys did was incredibly stupid. >> incredibly. >> reporter: fishing guide and resort owner speedy colett says.