An in-vivo device, system and a method for imaging a body lumen, typically liquid filled body lumen. The in-vivo device may have a specific gravity of about 1 or a volume to weight ratio that enables it to float. The in-vivo device may include an optical system for viewing through a body lumen liquid and another optical system for viewing through a non liquid medium. The in-vivo device may be moved through the body lumen by the liquid movement in that lumen.
