The Ambergris Element ( episode ) The crew of the " Enterprise " explore a submerged culture on a water world . Summary . The crew lands on the water in a specially designed aqua - shuttle , but this immediately comes under attack from a giant sur - snake . After the creature is fired upon by the aqua - shuttle ' s onboard phaser s , Captain Kirk orders that the shuttle submerge and take a closer look at it before the stun wears off . The creature quickly regains consciousness however , and continues its attack . Kirk opens his communicator and asks Scott to beam them up , but the sur - snake grabs the shuttle and throws it against the rocks . Lieutenant Clayton and Dr . McCoy are thrown clear and fall into the water , but Kirk and Spock are still in the shuttle and disappear when the vessel submerges in the being ' s grip . McCoy , Scott , and Lt . Clayton find the missing officer s , both with strange mutation s . Kirk and Spock are inside a tank filled with water . McCoy says through an intercom , " " We ' re stumped , Jim . The hormone seems to be the major factor in your mutation , but we just can ' t identify it . " " Kirk asks , " " Are you sure the mutation wasn ' t somehow accomplished naturally ? " " McCoy replies , " " It ' s infused into your bodies at key structural points . It had to be done by injection . " " Kirk demands , " " But can ' t you duplicate it , Bones ? Your medical computer s have information of every procedure in the Federation ' s hospitals . " " McCoy says , " " It ' s highly sophisticated , and completely unknown to us . " " Spock inserts , " " That implies there are intelligent lifeforms on Argo . " " McCoy replies , " " The sensor s don ' t indicate any life forms down there aside from fish . " " Spock thinks the readings may be incomplete . Since Kirk cannot spend the rest of his life confined to a tank , least of all command the " Enterprise " from inside one , he and Spock are forced to return to the planet and travel underwater to find the planet ' s inhabitants , whose name for themselves proves to be " Aquan s , " in the hope that these will be able to return them to their normal Human and Vulcan selves . Kirk and Spock explore the submerged Argo and find a group of inhabitants who hate and fear air - breathers . They want them to leave . Their young saved them once but it will not happen again . The two officers soon find a beautiful underwater city and are promptly taken prisoner . Hesitantly , the Aquans agree to perform surgery to return Kirk and Spock to normal , but when Scott dives down to warn of an impending quake , they become fearful of air - breathing spies . Kirk and Spock are deemed treacherous and are sentenced to death by forced suffocation . Rila , a water breather , agrees to help them if they will in turn help her find a buried ancient city in ruins whose archives may contain a way to reverse the mutation . They discover that the substance in their bloodstreams is similar to the ambergris of Earth whale s . The reverse mutation is induced by an infusion of an antitoxin made from the venom of a deadly giant sur - snake . The Aquans help them obtain the necessary medicine , but Kirk nearly dies from the vaccination . In orbit , the uses its phasers to blast uninhabited sections of the planet in an attempt to move the quake ' s epicenter away from the Aquan city , and also causes an inadvertent side effect : new land masses emerge from beneath the oceanic surface . Grateful for saving their lives , the young Aquans make their ancient records available to the Federation and inexplicably decide to use the newfound medicine to become air - breathers themselves and resume life above - ground . Kirk implores them not to lose contact with their underwater ancestors . The elders declare they will pass ordinances to forbid that and this time they will not ignore them . Memorable quotes . " " What the devil was that thing ? " " " " Apparently a lifeform which previous surveys have not recorded . " " " " We ' ve lost contact , captain . Repeat , we ' ve lost contact . Come in , captain , come in ! " " " " Their bodies are functioning . Metabolism , heart , everything but the lungs ! " " " " Can ' t breathe . . . suffocating ! Help ! Can ' t breathe . . . " " " " What happened to them doctor ? What is it ? " " " " Something ' s changed their whole lung structure . They can ' t live in the air anymore ! " " " " Our equipment is too limited . " " " " We " aren ' t " limited . We can go wherever we want in that ocean . " " " " Look at this place . . . a tank ! I can ' t command a ship from inside an aquarium – I can ' t LIVE in here ! " " " " It is quite possible , captain , that they find us grotesque and ugly and many people fear beings different from themselves . " " " " Apparently , they were exposed to a frightening geological disaster . Such hardship induces savagery and violence . " " Links and references . References . air - breather ; algae ; ambergris ; antitoxin ; Aqua - City ; Aquan s ; Aquan ordainments ; aquarium ; aqua - shuttle ; architecture ; ; blood ; " Bones " ; boulder ; cold ; continental shelf ; Denebian whale ; devil ; directional marker ; dizziness ; dose ; drowning ; Earth ; edibles ; evolution ; exile ; eye ; eyelid ; fern ; fish ; geological disaster ; gill s ; heart ; hereditary trait ; High Tribune ; hormone ; injection ; instinct ; Junior Tribune ; life support belt ; logic ; lung s ; medical computer ; memory wipe ; mesh ; metabolism ; mile ; Milky Way Galaxy ; mutation ; NCC - 1701 \ 5A ; NCC - 1701 / R6 ; ocean ; power pack ; pressure ; pulse ; reef barrier ; respiratory system ; Ruling Tribunal of the Aquans ; scientist ; scouter - gig ; sea foliage ; seaquake ; seawater ; seismic ; serum ; skeleton ; spy ; suffocation ; surgo - op ; surgo - record s ; sur - snake ; survey ; telefocals ; tide s ; topography ; torso ; tribune ; universal translator ; venom ; water - breather ; water mask ; web ; whale