Today I watched my sister's 60 year old tortoise quite deliberately walk in to her pond and drop to the bottom. She leapt in and dragged it out as we both thought tortoises drown. It seemed to go into this deep pond(knee high) very deliberately and to be walking along the bottom when she fished it out. It has been found covered in green weed once before. What do you think this behaviour was all about? Suicide? Do you think tortoises can hold their breath under water for a considerable period of time? Where can I find out about this?