Level 1: In-town trail over streets, sidewalks, stairs, city parks, etc.
Level 2: Urban, with some off-road, but no significant mud or water.
Level 3: Some ready-made paths but also some trailblazing through wooded areas and maybe some splashing through shallow water or mud.
Level 4: Mostly wooded trailblazing and/or swamp or water crossings that could be as high as an average guy’s waist. Swamp can range from murky black water to shoe-sucking, knee-high mud. Could include crawling through dense or thorny underbrush and obstacles such as fences, walls, mud, muck and possible hazards such as oyster shells and trash.
Level 5: Anything goes. Could include dense underbrush, briars/thorns, obstacles, shoe-sucking thigh-high mud, and water possibly above one’s head. In Level-5 shiggy, you should have a trail buddy with you at all times.