RIO Premier Fathom Sinking Fly Line Review

1 comment /
RIO Premier Fathom Sinking Fly Line Review

There are undoubtedly many people whose minds immediately conjure up images of the very popular movie "A River Runs Through It" when you say the words “fly fishing”. Graceful dry line casts, trout sipping dry flies off the surface…ah the dream!  Well, while this is the dream, the reality is a lot of our BC fly fishing occurs sub-surface.

We are going to review the RIO Premier Fathom Sinking Fly Line, a line that will help you live the sub-surface dream of fly fishing. This line has a short, powerful 35’ head, landing it right in the middle of two very popular RIO floating lines, the RIO Grand (38’ head) and the RIO Outbound Short (30’ head).

The Premier Fathom has a nice supple core to prevent line tangles. It’s looped on both ends for fast and easy connection to backing and tapered leaders.

RIO Premier Fathom Review

Short Head Design

The head is easily identifiable by a noticeable colour change between the head and the running line. This makes it easy to know where your optimal loading point is. For eons, sinking lines were one colour, so this is a very refreshing change in fly line design. 

This short head allows anglers to load up their rods quickly with less false casting, keeping the fly in the water more throughout the day. Seeing as the fish are in the water and not in the air, this increases the chances of success substantially. 

The shorter head can be very advantageous to those who are just getting into fly fishing. Having too much line in the air can be a challenge to those just starting out, so having a loaded rod with little line out helps, no question.

Density Compensated

The RIO Premier Fathom Sinking Fly Line is density-compensated so that it sinks without a belly in it. This allows you to fish a truer depth. Sinking lines that are not density compensated, because of the weight forward design, are heaviest back from the tip of the fly line, so the heavier section sinks faster while the tip of the line, being lighter, will be higher in the water column.

Hang Marker

The Premier Fathom also comes with a Hang Marker. This is an indicator that you’re getting close to the end of your retrieve. At this point your retrieve should be paused, giving the fly a static presentation and hopefully producing a strike from an interested fish.

SlickCast Technology

We’ve saved the best for last. The Premier Fathom utilizes RIO’s SlickCast technology, making this line unbelievably slick and allowing you to cast it even further. It’s quite amazing. The SlickCast technology helps to increase the fly line’s durability too. You can tell that this line will sail through the guides of your fly rod when you take it out of the packaging.

Line Weights

The Premier Fathom is available in WF5-WF8 and in sink rates of 3ips, 5ips and 6ips.


The RIO Premier Fathom is truly a dream come true for sub-surface fly fishing. We hope that you’ve enjoyed and benefited from this review of the RIO Premier Fathom Fly Line.

If you have any questions about this fly line, please feel free to contact us by email, by phone at 604-931-5044 or stop by 

Sea-Run Fly & Tackle at #110 1140 Austin Avenue in Coquitlam BC.

Good luck on the water.

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1 comment

  • by Terry

    I fished this line in Puget Sound from a boat just South of Seattle in August of 2023. It was not by boat so the owner was reluctant to leave the downriggers and go to fly rods. Finally he agreed to switch. I used a hot pink and white Dolly Llama fly. We were trolling at about 3 mph . You could tell that my line was much deeper than the other two fly rods due to the density compensation of this line. I proceeded to hook about a fish every 10 minutes to there zero. Most were release as I am not a fan of pink salmon no matter what anyone says about eating them the same day. I also landed a beautiful 26" Coho.

    I started fishing a density compensated type 6 line on my six weight about a year ago in lakes and had similar results fishing trout. I have given away my older full sinking lines.

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