This is the third and apparently final installment of the Groundtruther series, in which guitarist Charlie Hunter and drummer/electronics manipulator Bobby Previte provide the foundation for a series of performances with a rotating cast of artists to round out the "trio." Prior recordings were Longitude, with DJ Logic and Latitude, with Greg Osby. On Altitude (Thirsty Ear THI-57181), keyboard whiz John Medeski is the featured guest. This is a specially priced double disc, consisting of an acoustic set ("Below Sea Level") and an electric set ("Above Sea Level"). "Below Sea Level" virtually defies expectations, as guitar, piano, melodica and drums weave in and out of compositions which in large part sound more like modern classical/avant-garde than jazz. This is a recording which demands attention from the listener. "Above Sea Level" is a different animal altogether, with "Taipei" blending electronica with jazz-rock, while "Pyramid of Giza" seems influenced by early Pink Floyd or Tangerine dream. Some of the pieces here would be at home on Hunter's Mistico, while "Seoul Tower" at times approaches the intensity of John McLaughlin's early classic, Devotion. All three of the artists here are versatile, talented and unafraid to experiment and both the acoustic and electric sets amply demonstrate these qualities.