The StompBox™ — Hala's Patented Retractable SUP Fin
Hit a rock. Keep paddling.
The patented StompBox™ holds a full 9″ center fin at full depth with twin springs driving active downward pressure. Strike a rock and the fin tucks fully into the board, then springs back before your next stroke. No bobbing. No wobble. No swimming.
US Patent 10,046,836 · Standard on every Hala river board · Only from Hala Gear
Before the StompBox, river paddlers had two bad options: run a real fin and risk snagging a rock — the jolting stop that launches you over the nose — or swap to a stubby fin and give up tracking, drive, and stability.
We refused to choose. So we engineered a fin that does both, patented it, and put it on every river board we make.
Full-size fin. Zero hesitation.
The fin meets the river bottom
Your 9″ StompFin™ contacts a rock or gravel bar in shallow water — the moment that used to end your line.
It tucks fully into the board
The fin retracts completely inside the box. Nothing left hanging below the hull to catch, drag, or break.
It springs back to full depth
Twin springs drive the fin back down before your next stroke — already tracking, already driving.
Active downward pressure. Not gravity. Not luck.
Most retractable fins just hang there — held down by gravity and hope. In moving water they bob up and down and slop side to side, and every bounce costs you tracking exactly when you need it.
The StompBox 2.5 is different: two springs actively drive the fin down and hold it at full depth through current, boils, and turbulence — precise performance and stable power transfer for surfing, tracking, and ferrying.
- No bobbing up and down — the fin is under constant downward load
- No side-to-side wobble — the fin is held rigid in its box
- Full depth, all the time — until a rock says otherwise, and then it springs right back
Stomp it down. Watch it spring back.
One fin that surfs, tracks, and drives — and gets out of the way the instant the river gets bony.
Six precision parts. A decade of refinement.
The StompBox 2.5 is a machined system: fin box, cover, 9″ SpringFin, center spring, spacer, and screws — a twin-spring design for precise, stable power transfer, with every component available as a spare, so one worn part never means a new board.
The whole box is removable in minutes. Pull it when the board is deflated and your board rolls down to its most compact — airline, bus, and closet approved.
Curious how the system goes together? See the StompBox 2.5 kit →
What a full-size fin under constant pressure gets you
Tracking, speed & drive
Paddle forward more, correct less. Ferry, attain upstream, and hit your line with precision — a full 9″ fin that never lifts off takes the scoop out of every stroke.
Confidence in shallow water
Run rocky, bony, low-water sections without planning around your fin. It retracts when it must and springs back when it can.
Stability & surf
Constant twin-spring pressure means constant side-to-side stability and clean power transfer — and a longboard-inspired fin shape that holds a wave face instead of washing out.
Stealth for fishing & expeditions
Track across deep water fully loaded, then slide silently through skinny flats — same board, same fin, no swaps mid-mission.
Travel-size packability
The removable box lets your deflated board roll down to its most compact for travel and storage. Carry a spare kit on expeditions for total peace of mind.
A faster learning curve
High-rocker river boards spin without the right fin. With a full fin locked down beneath you, your energy goes into paddling — not correcting.
Reviewers keep saying the same thing
“Riding the Hala Atcha 86 is like dropping into the river on a skateboard.”
Paddling Magazine · 2026 Best Whitewater SUP Award
“The StompBox fin system is really quite nice… it holds securely in place. The StompBox 9″ retractable fin gives the Atcha 86 more hold in the current.”
Inflatableboarder.com · Independent Review
“No worry when paddling over shallow rocks — the StompBox makes paddling shallow rivers easy.”
Hala Customer Review · Read Hundreds More
Not every “retractable fin” is a StompBox
A decade of on-river refinement is hard to copy. If you’re shopping retractable fins, ask these six questions of any system — here’s how the StompBox 2.5 answers them, and what we found when we took apart the alternative.
| StompBox™ 2.5 | Other retractable fins | |
|---|---|---|
| Hold-down force | ✓Active twin-spring pressure holds the fin at full depth through current and turbulence | ✗Passive — the fin relies on gravity, bobbing up and down in moving water and losing bite |
| Lateral hold | ✓Fin held rigid in a machined box — no play, tracks true | ✗Fin flops side to side under light hand pressure — that slop is your steering |
| Retraction | ✓Retracts fully into the board — nothing left below the hull to catch | ✗Only partial retraction — the fin still hangs below the board when “retracted” |
| Leading edge | ✓Clean leading edge — no exposed hardware where rocks hit first | ✗Retention screw sits on the fin’s front edge — the first point of impact, and it can break |
| Retention system | ✓Engineered twin-spring system, machined components, every part field-replaceable | ✗A rubber band and a racquetball. We’re not joking. |
| Fit & drag | ✓Box sits flush with the hull — clean water flow, nothing to snag | ✗Housing deforms and sits proud of the board — constant drag and a snag point |
Based on our hands-on teardown of a leading competitor’s retractable fin system, July 2026. We’ll let the engineering speak for itself.
What do you want to do on the water?
Whitewater & River Running
Precision and drive through rapids, with a fin that gets out of the way when the river gets bony.
Shop Whitewater SUPs
River Surfing
A longboard-style fin under constant pressure that holds a wave face without washing out.
Shop The Charge Series
Fishing
Track across deep water, then slide silently into the shallow flats where the fish actually are.
Shop Fishing SUPs
Expeditions & Overnights
Load your gear on a board that tracks fully loaded and shrugs off shallow gravel bars.
Shop The Adventure SeriesEvery Hala river board comes with the StompBox 2.5 — included
Four boards, one patented fin system. Pick by how you paddle. Every board ships as a complete kit with the StompBox 2.5 — $1,399 lineup-wide, backed by a 5-year warranty.
Atcha 86
Sporty Whitewater & River Surf
8′6″ of playful, surfy agility. “Like dropping into the river on a skateboard.”
Atcha 96
The Original Whitewater SUP
9′6″ × 36″ — the shape that defined whitewater SUP since 2013. Stable, surfy, proven.
Rado
River + Expedition + Fishing
10′10″ × 35″ for paddlers who want it all: whitewater capability and a gear-hauling platform.
Radito
The Nimble Expedition SUP
The Rado’s go-anywhere capability in a lighter, more compact package (~22 lbs).
Not sure which board fits you?
Answer six quick questions and we’ll match you to your board — or compare all four side by side.
Already ride a Hala?
The StompBox 2.5 fits every Hala river board from 2021 on. Replace a well-loved box, carry a spare for expeditions, or boost a StompBox 2.0 to 2.5 performance. Watch the 2-minute install.
StompBox FAQ
What exactly is the StompBox?
The StompBox™ is Hala’s patented (US Patent 10,046,836), spring-loaded, fully retractable 9″ center fin system. Twin springs apply active downward pressure, holding the fin at full depth through current and turbulence; when the fin hits a rock or the river bottom, it retracts fully into the board and springs back automatically. It has been the most desired feature in whitewater SUP since its introduction in 2015, and it’s available only on Hala boards.
How is the StompBox different from other retractable fins?
Three things: force, retraction, and build. The StompBox 2.5 uses two springs applying active downward pressure to hold the fin at full depth — precise performance and stable power transfer for surfing, tracking, and ferrying — so it never bobs up and down or wobbles side to side in current the way passive, gravity-held fins do. It retracts fully into the board rather than partially. And it’s a machined, field-serviceable system — not a fin held in by a rubber band, with no exposed screw on the leading edge waiting to hit a rock.
Which boards come with the StompBox?
Every current Hala river board includes the StompBox 2.5 as standard: the Atcha 96, Atcha 86, Rado, and Radito.
Does it help on flatwater and lakes, or just rivers?
Both. On deep, flat water you get full-size-fin tracking under constant pressure, so you paddle forward more and correct less. The retraction only comes into play when the fin contacts something — which is exactly when you want it to.
What happens if I hit a rock going fast?
The fin deflects and retracts cleanly instead of snagging, so the board keeps moving and you stay on it — no “supermanning” over the nose. The fin is flexible, so off-axis impacts won’t break it. It retracts on forward impact, so be mindful when paddling backwards.
Can I replace or upgrade my StompBox?
Yes. The entire box is removable and swappable in minutes, and every component is available as a spare. The StompBox 2.5 Full Kit ($99) fits all Hala river boards from 2021 onward, and the Booster Kit ($45) upgrades a StompBox 2.0 to 2.5 performance.
Does removable mean it can fall out?
No — the board’s inflation pressure (15 PSI) locks the box firmly in place, flush with the hull. Removability is a travel feature: pull the box when deflated and your board rolls down to its most compact for travel and storage.
Paddle wherever you want.
Rivers, rocks, shallows, waves — the StompBox means you stop planning around your fin. Every Hala river board ships with it, backed by a 5-year warranty.