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A COMPLETE SERIES OF SINKING LINES DESIGNED for easy distance and complete fly control

Fathom Sinking Lines


RIO’S FATHOM LINES are a series of sinking lines designed specifically for the lake angler. Each line has a short, quick-loading head for minimizing the number of false casts, and for quick, easy distance, and a color contrast between the head and the running line to easily show the line’s loading point. In addition, each line is built with a Hang Marker that shows anglers when to stop stripping, and when to fish the “hang”, and features RIO’s “Density Compensation” (except type 7) for complete fly control.

taper profile


Extreme Slickness

Extreme Slickness technology is a chemistry formulation that results in an ultra- slick line with dirt-repelling properties.



Marks the sweet spot of a fly line by providing an obvious color change in the line at the sweet spot.


RIO’s printed line marking system that allows anglers to quickly and easily identify each line.

Front Welded Loop

A neat, bulletproof loop welded at the front of the fly line for fast rigging to a leader.

Back Welded Loop

A neat, bulletproof loop welded at the end of the fly line for fast rigging to backing.

Density Compensation

Adds a denser material to the thin tip of a sinking line (or sink tip), which ensures the line sinks straight.

Hang Marker

A visible, 1” section built into the fly line that show anglers when the end of the sinking line is getting close.

Fathom Sinking Lines - All Models

Line ColorSink RateLine Size
Black/Blue 3ips WF5S3
Black/Blue 3ips WF6S3
Black/Blue 3ips WF7S3
Black/Blue 3ips WF8S3
Black/Maroon 5ips WF5S5
Black/Maroon 5ips WF6S5
Black/Maroon 5ips WF7S5
Black/Maroon 5ips WF8S5
Black/Green 6ips WF5S6
Black/Green 6ips WF6S6
Black/Green 7ips WF7S6
Black/Green 6ips WF8S6
Black/Gray 7ips WF6S7
Black/Gray 7ips WF7S7
Black/Gray 7ips WF8S7