Thanks. I looked at Wikipedia to see how they operate. I don't feel like signing up as a member with SubCommittee. I am not interest in owning and operating r/c subs, but only in their basic theory of design and operation. I guess they could be dived in a large glass fish tank as at city aquariums to be observed through the glass underwater or in a swimming pool with a port hole under water to view them clearly. I thinks camera are put in some of them too but they allow the submarine itself to viewed underwater.