Simple categories matching underwater:

• structure,
• killer,
• object,
• location,
• mission,
• means,
• disturbance,
• surface,
• substrate,
• connection,
• weaponry,
• use,
• creature,
• facility,
• installation,
• feature,
• animal,
• artifact,
• missile,
• area,
• grass,
• life,
• plant,
• sport,
• weapon,
• organism,
• projection,
• predator,
• instrumentation,
• happening,
• craft,
• cetacean,
• vehicle,
• cave,
• metal,
• shock,
• operations,
• task,
• mound,
• heritage,
• prey,
• mammal,
• inhabitant,
• world,
• material,
• job,
• experience,
• gear,
• function,
• munition,
• worker,
• duty,
• part,
• information,
• activity,
• equipment,
• work,
• resource,
• substance,
• wonder,
• shape,
• body,
• service,
• ordnance,
• operation,
• unit,
• article,
• prop,
• formation,
• explosive,
• event,
• system,
• native,
• construction,
• vessel,
• appendage,
• obstruction,

Members with property underwater:

• structure,
• fish,
• seal,
• swordfish,
• earthquake,
• pier,
• shark,
• submarine,
• seaweed,
• weedy_area,
• canyon_system,
• ray,
• missile,
• hydrofoil,
• bow,
• underwater_vessel,
• leaking_gasket,
• dugong,
• dolphin,
• log,
• stone,
• pier_structure,
• flare_jetty,
• weed_bed,
• pipeline,
• plant,
• bridge,
• wellhead,
• rescue,
• outfall_pipeline,
• reservoir,
• small_fish,
• lead_cable,
• signal_repeater,
• ship_wreck,
• hungry_fish,
• bottom_contour,
• intake_pipe,
• jetty_pylon,
• dolphin_playing,
• junction_box,
• obstacle,
• fin,
• abutment,
• tadpole,
• bottom_surface,
• mechanical_shark,
• quay,
• building,
• mine,
• search,
• boat_bottom,
• photography,
• gas_pipe,
• practice_mine,
• shaft,
• swimming,
• research,
• diving,
• oxygen_weeds,
• widgeon_grass,
• vinyl_bag,
• dam_foundation,
• branch,
• repair,
• snail,
• crocodile,
• crustacean,
• fin_swimming,
• centerboard,
• shoal_area,
• channel_wall,
• fish_cage,
• water_sewage,
• breakwater_caisson,
• starfish,
• bridge_pier,
• debris,
• oil_platform,
• sharp_metal,
• lake,
• lobster,
• platform_legs,
• communications_system,
• sonar_head,
• underwater_pipe,
• diving_beetle,
• fountain,
• surveillance,
• cable,
• template,
• tropical_fish,
• tree_limb,
• pallet,
• transponder,
• wharf,
• pillar,
• trim_tab,
• gas_exploitation,
• soil,
• shrimp,
• hockey,
• wood,
• porpoise,
• grouper,
• spinner,
• installation,
• spear_fishing,
• shoreline,
• bow_dome,
• spur,
• inshore_reef,
• investigation,
• creek_channel,
• ridge,
• manatee,
• draft_tube,
• barnacle,
• rugby,
• dock_piling,
• continental_shelf,
• owl,
• school,
• grass_bed,
• monkfish,
• oil,
• sea_mine,
• stern_tube,
• wreck,
• pool_spa,
• sea_shell,
• mooring,
• twig,
• crayfish,
• banana-boat_ride,
• limb,
• sampling,
• landslide,
• lobster_hunting,
• oceanic_survey,
• tv,
• plant_stem,
• harpoon,
• scallop,
• diving_bird,
• kelp,
• lobster_trap,
• harbor_wall,
• bandtail_searobin,
• newt,
• intake,
• silver,
• sample_collection,
• aquatic_vegetation,
• rock_piling,
• mining,
• deep_hole,
• tank,
• canyon,
• jellyfish,
• inspection,
• fishnet,
• sloping_embankment,
• steps,
• water_inlet,
• bottom,
• spear_gun,
• ceramics,
• stilling_basin,
• record,
• turtle,
• exploration,
• fish_bed,
• boat,
• easement,
• reed,
• canal,
• prey,
• autonomous_vehicle,
• inspection_work,
• breakwater,
• shell,
• seabed,
• dam_wall,
• current_meter,
• underwater_rugby,
• side,
• sculpin,
• trench,
• anchor_work,
• barracuda,
• worm,
• barge,
• underwater_photography,
• spa,
• piling,
• beluga_whale,
• dangerous_obstruction,
• moray,
• cofferdam,
• turbine_hydrofoil,
• swimming-pool_bottom,
• jetty,
• strong_earthquake,
• drift_dive,
• mountain,
• field,
• keel,
• artificial_structure,
• rocky_bottom,
• strut,
• tunnel,
• underwater_camera,
• marine_bird,
• compressor,
• barrels,
• ocean_mine,
• sink,
• digital_camera,
• rafts_figure,
• octopus,
• pier_footing,
• weeds,
• otter,
• wreck_diving,
• squid,
• channel_bed,
• bronze,
• harbour,
• snorkeling,
• cable_laying,
• ship,
• optical_fibre,
• dam,
• lock_gates,
• bottle,
• hole,
• harbour_facility,
• boat_hull,
• wall,
• geological_feature,
• sunken_vessel,
• crabs,
• cuttlefish,
• manta,
• glider,
• pond_weeds,
• weir,
• harbor,
• cement_wall,
• eel,
• piece,
• bridge_pylon,
• dock,
• diver,
• seawater_gauge,
• marina,
• outlet,
• bedrock_dike,
• lump,
• pier_piling,
• spillway,
• camcorder,
• oil-production_platform,
• outlet_pipe,
• ship_hull,
• torpedo,
• night_diving,
• communication_line,
• gold_fish,
• bolt_pistol,
• air_tube,
• hippopotamus,
• levee,
• acoustic_release,
• shipwreck,
• military_installation,
• obstruction,
• coral_head,
• clay_ridge,
• swimmer_weapon,
• trough,
• enemy_submarine,
• embankment,
• dock_post,
• stingray,
• frill_shark,
• sea-bottom_survey,
• net_pen,
• survey,
• runoff_pipe,
• bridge_footing,
• oilrig,
• steel_structure,
• nozzle,
• shelf_edge,
• sunken_ship,
• tuna,
• rock,
• whale,
• bridge_piling,
• diver_delivery,
• volcanic_activity,
• fence,
• dike,
• submersible_pump,
• underwater_cleanup,
• remote_sensor,
• propeller,
• scuba_gear,
• marine_mammal,
• feeding,
• lamprey,
• ascidian,
• mudslide,
• hot_tub,
• pool,
• shelf,
• quay_wall,
• port_structure,
• bulkhead,
• aquatic,
• bulbous_bow,
• spearfish_torpedo,
• pallet_structure,
• telecommunication_cable,
• yacht_hull,
• pondweed,
• small_submarine,
• sonar_transducer,
• harbour_works,
• bladderwort,
• day,
• rocket,
• reef,
• bat,
• ship_bottom,
• lock,
• earthquake_cause,
• rock_bed,
• water_intake,
• doppler_log,
• leech,
• aquatic_insect,
• silt_pocket,
• stump,
• frog,
• eel_grass,
• pike,
• shellfish,
• sea_wall,
• manned_submersible,
• turbine,
• thruster,
• muscle,
• exploration_point,
• leopard_seal,
• corral_reef,
• seahorse,
• propeller_shaft,
• vegetation,
• sonar_devices,
• electric_motor,
• platform,
• volcanic_eruption,
• net_cage,
• reef_structure,
• estuarine_dolphin,
• historic_wreck,
• harbor_structure,
• spinner_dolphin,
• stork,
• deflector,
• reconnaissance,
• seabed_facility,
• swimmer,
• electric_eel,
• stick,
• pipe,
• valve,
• pipe_end,
• ladder,
• aquarium,
• quirky_square,
• underwater_hockey,
• vessel_hull,
• underwater_plant,
• scientific_exploration,
• commercial_aircraft,
• riser,
• milfoil,
• unexploded_torpedo,
• construction,
• eelgrass,
• submersible_vehicle,
• seamount,
• coral,
• rudder,
• turtle_cavern,
• sand,
• hull,
• lead,
• algae,
• burning_gear,
• chains,
• hard_edge,
• defence_works,