Home / Shop / Freshwater / Fly Lines / Fathom Sinking Lines

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 Spey-specific rigging.

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