Modifiers matching obstruction:

• physical,
• visible,
• current,
• under,
• permanent,
• temporary,
• large,
• featureless,
• past,
• vertical,
• solid,
• hidden,
• immovable,
• major,
• dense,
• underwater,
• up,
• hazardous,
• discrete,
• virtual,
• larger,
• visual,
• artificial,
• lighted,
• indoor,
• mechanical,
• nasal,
• insurmountable,
• multiple,
• lateral,
• spatial,
• underground,
• subsurface,
• nearby,
• overhead,
• significant,
• terrestrial,
• over,
• external,
• horizontal,
• opaque,
• urethral,
• isolated,
• hydraulic,
• tall,
• impenetrable,
• layer,
• linear,
• irregular,
• common,
• outdoor,
• short,
• unusual,
• fixed,
• bigger,
• low,
• upright,
• cooler,
• natural,
• adjacent,
• rigid,
• relevant,
• local,
• smaller,
• movable,
• topical,
• geographic,
• taller,
• metal,
• level,
• removable,
• raised,
• typical,
• surrounding,
• elongated,
• additional,
• clear,
• electrical,
• structural,
• small,
• environmental,
• internal,
• minor,
• hard,
• simple,

Simple categories matching underwater:

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