Question: Headin' Down Into the Mystery Below, is an album by American musician John Hartford, released in 1978, John Cowan Hartford (December 30, 1937 – June 4, 2001) was an American folk, country and bluegrass composer and musician known for his mastery of the fiddle and banjo, as well as for his witty lyrics, unique vocal style, and extensive knowledge of which location's lore?

Context paragraphs:
Old and in the Way: Old and in the Way was a bluegrass group in 1973.  It was composed of Peter Rowan (guitar, vocals), Vassar Clements (fiddle), Jerry Garcia (banjo, vocals), David Grisman (mandolin, vocals), and John Kahn (string bass).  When the group was forming, it was intended that John Hartford would be the fiddle player.  Based on Hartford's engagements, and Clement's reputational stature in the bluegrass community, Clements became the group's fiddler.

Goin' Back to Dixie: Goin' Back to Dixie is a bluegrass album by American musician John Hartford, released in 1992 (see 1992 in music).

All in the Name of Love (John Hartford album): All in the Name of Love is a bluegrass album by American musician John Hartford, released in December 1977 (see 1977 in music).

John Hartford: John Cowan Hartford (December 30, 1937 – June 4, 2001) was an American folk, country and bluegrass composer and musician known for his mastery of the fiddle and banjo, as well as for his witty lyrics, unique vocal style, and extensive knowledge of Mississippi River lore.  His most successful song is "Gentle on My Mind" which won three Grammy Awards and was listed in "BMI's Top 100 Songs of the Century".  Hartford performed with a variety of ensembles throughout his career, and is perhaps best known for his solo performances where he would interchange the guitar, banjo, and fiddle from song to song.  He also invented his own shuffle tap dance move, and clogged on an amplified piece of plywood while he played and sang.

The Fun of Open Discussion: The Fun of Open Discussion is a bluegrass album by American musician John Hartford and Bob Carlin, released in 1995 (see 1995 in music).

Old Sport: Old Sport is a bluegrass album by American musician John Hartford and Texas Shorty (Jim Chancellor), released in 1995 (see 1995 in music).

No End of Love: No End of Love is a bluegrass album by American musician John Hartford, released in 1996 (see 1996 in music).

The Walls We Bounce Off Of: The Walls We Bounce Off Of is a bluegrass album by American musician John Hartford, released in 1994 (see 1994 in music).

Headin' Down into the Mystery Below: Headin' Down Into the Mystery Below is an album by American musician John Hartford, released in 1978.  All the songs, written by Hartford, continue to show his love for steamboats and the Mississippi River.  It is currently not in print.

Aereo-Plain: Aereo-Plain is American musician John Hartford's groundbreaking bluegrass album released in 1971.  It reached number 193 on The Billboard 200 chart.

Supporting paragraphs: Headin' Down into the Mystery Below John Hartford
Answer: Mississippi River