Add rice krispies and sea salt to a large mixing bowl.
Prepare a 9x13 rectangle pan with non-stick cooking spray.
Melt caramel in a microwave-safe bowl for 45 seconds. It should be soft and able to stir. If not, microwave in additional 15-second intervals until you can stir it easily.
Melt butter and marshmallows in a separate bowl for 2 minutes.
Add caramel to butter and marshmallows and stir until smooth.
Add butter, marshmallows, and caramel immediately to the rice krispies. Stir until well combined.
Place into the 9x13 pan. Wet your hands and press down on the mixture to make it even across the pan. Sprinkle a little additional salt if desired.
Let cool.
Note: Do not refrigerate. It will harden the sugars and make your rice krispie treats impossible to eat.