Ok this might not be the place for it as it wasn’t a proper movie, it was like a movie that had been split in half and only appeared on tv once.
It featured a family that moved near the sea in a hamlet where there was a secret research laboratory with an shark that was attacking and killing things. There was a hobo like man who knew about it.
When they found the lab and entered down a ladder they found this shark that had legs and could walk as it was some genetics experiment mixing the hobo mans (who used to work at the lab) DNA with that of a great white.
Hobo man ends up sacrificing himself to stop it I think. I must have seen it over 12 years ago. It was in colour.