If something is supersafe, it is very, very safe and there is almost no chance of getting hurt.
Supersafe makes people think of being protected and not having to worry about anything bad happening.
Examples:
The seatbelt is supersafe.
My house is supersafe because it has a big fence.
The supersafe lock kept the treasure safe.
I feel supersafe with my big brother around.
The superhero's cape is supersafe and can protect from anything.
The supersafe net caught the falling cat.