Aquazone Aquazone was an underwater theme first introduced by the LEGO Company in 1995 . The setting of all the Aquazone lines was the ocean , and usually involved two sides fighting each other for certain valuables ( such as Hydrolator Crystals and other treasures ) . As the series progressed , new factions were introduced and the older ones were phased out of production . There were five subthemes of Aquazone . Its last new releases were in 1998 . Aquazone was the second entirely new " " LEGO System theme ( after Pirates ) that was introduced after the initial three classic major themes Town , Castle , and Space from 1978 . History and Factions . Aquanauts ( 1995 - 1996 ) . In the original Aquazone line , the heroic Aquanaut miners fought against the villainous Aquasharks and their leader , Thresher , for control of the crystal mines . The Aquanauts were a group of miners based at the Neptune Discovery Lab , who utilized submarines and submersibles of all shapes and sizes to look for Hydrolator crystals , which they depended on for survival and possibly trade . The yellow base colour of the subs and the bowl - shaped cockpit pieces gave the Aquanauts a rather realistic appearance that was close to actual mini submarines . However , the second wave in 1996 brought a vessel that featured wheels . Aquasharks ( 1995 - 1996 , 1998 ) . The Aquasharks were villainous underwater miners who competed with the Aquanauts for control of crystals and crystal mines . The Aquashark subs sported a colour scheme that was similar to Space Police I and their streamlined design , with eyes and shark teeth on the cockpit windows giving them an aggressive appearance . In 1998 the set 6100 Aquashark Dart was released . The colour scheme was unlike any previous Aquashark set . Only the minifigure ' s torso was a distinct Aquashark piece . Aquaraiders ( 1997 ) . In 1997 , the Aquanauts and Aquasharks subthemes were discontinued and the Aquaraiders were introduced as an alternate villain faction that competed with both the Aquanauts and Aquasharks . Their fleet consisted of three vessels in black with green accents and trans - neon green window pieces . The front windows sported stickers with angry eyes on them . The ships had accessories that looked like drills and grinders and had quite an exotic look for submarines . ( Note that actual drills were not introduced until the release of Rock Raiders in 1999 ) . One " ship " even featured an excavator bucket . Another one had wheels . The focus changed from simply collecting crystals to underwater mining . A new theme called Aqua Raiders was introduced in 2007 . This was not a part of Aquazone . Hydronauts ( 1998 - 1999 ) . The final years in the Aquazone line involved a battle between the Hydronaut miners and the fish - like Stingrays . One of the main differences was that the Hydronauts would actually capture the Stingrays and lock them up in the Hydro Crystallization Station . The protagonists included Hank Hydro , Hip Waders , and Crystal Miner . The colour scheme was similar the one of the Aquanaut line , the only difference being the transparent pieces which were now exclusively transparent green instead of blue and trans - neon orange . But the designs looked even more exotic than in 1997 . Like the Aquanauts and Aquaraiders , the Hydronauts had also a wheeled underwater vehicle , but unlike their predecessors from 1997 , they didn ' t make any use of drilling equipment . The minifigures had unique masks printed onto their faces which gave them a very alien look . The Hydronauts used suction cups to move their storage boxes in contrast to the commonly utilized magnets . Stingrays ( 1998 ) . The Stingrays were fish - like mutants and enemies of the Hydronauts who used underwater vessels that resembled sea creatures like rays or crabs . The villains included Commander Manta Ray and Raven Ray , who despite his great intelligence , often found himself in a Hydronaut holding cell . New Pieces . With the start of the Aquazone line some new pieces that later became ubiquitous were introduced . However there were also some pieces that were never seen again outside of this theme .