No, you cannot use Dive in Pokemon Pearl to go underwater.
No, hamsters cannot scuba dive because they are not adapted for underwater breathing. Their respiratory system is not designed for underwater environments, and they would drown if submerged in water for an extended period of time.
The maximum safe depth for a human to dive underwater without any equipment is typically around 30 feet (9 meters). Diving deeper than this can lead to risks such as pressure-related injuries.
No, Pokemon who know HMs cannot be brought over through pal park, and the dive HM is not available in diamond and pearl, so it is not possible.
Use Dive.
Since dive is not a HM in firered you will have to trade a Pokemon to a friend that has ruby, sapphire or emerald then using that game use the HM Dive to teach the move Dive to that Pokemon trade it back so firered can have that Pokemon again it will still have Dive however you cannot use it to dive underwater.
No.
I don't think there is a sub, but you can get the tm dive to go underwater.
No!
maybe trying to dive.
the entrance is underwater you have to complete the phsychic gym to learn dive and dive near sootpolis island then you will find a path that leads to a sort of underwater cave and then click dive again to go up
You will need the Dive HM which I think you get from Stephen after getting the badge from the Mossdeep gym. Then use Dive out at sea and you can find shards underwater aorund the Mossdeep and Sootopolis areas.