it is a cave in sutopolis city.
the cave of origin is only in ruby and sapphire and emerald.
In the cave of origin.
The Cave of Origin is located in Sootopolis City...................... I hope that helps :)
You cannot get Kyogre in Ruby. You can only get Groudon in the Cave of Origin.
In the back of sootopolis city
In sootopolis's Cave of Origin