orange with spring strap
yellow with spring strap
blue with spring stap
pink with spring strap
black with rubber strap


Tech & Tips


Bio Fin Pro C-Series  (Spring Strap)


Brand does matter!  Apollo Bio Fins are the original and only split fin made from 100% natural rubber.


  • Auto adjust stainless steel spring strap
  • Oversized rubber heel protector for easy on/off
  • 100% natural rubber blade and foot pocket
  • Eliminates muscle cramping
  • Low Strain 20º angled blade works with the natural resting angles of ankle and knee
  • Easy finning for all levels of fitness
  • Increased maximum speed, reduced fatigue
  • Up to 40% reduction in muscle fatigue, energy output and air consumption; longest recorded bottom times during testing
  • Open toe foot pocket for added comfort
  • New Size XL Now Shipping
  • Videos | Awards | Test Scores
  • Closeouts Last Chance

Paddle Fins = Power on down stroke only

Bio Fins = Power on up and down stroke

Split Fin Technology Bio Fins provide lift and propulsion with less effort and more power.  Unlike other fins which "push" water up and down, Bio Fin blades direct water flow over the leading and trailing edges to provide power, lift and forward thrust on each stroke.  Apollo launched the original split fin in 1998.  Over 15 years of rave reviews and awards, no other fin has beaten the consistently high scores awarded by Scuba Lab and Scuba Gear Reports. Dare to compare.  Grab a copy of latest Scuba Lab review then click here to compare with previous testing of Bio Fins.

100% Natural Rubber - Only From Apollo Superior to any synthetic or hybrid material, Bio Fins are the only split fins made from 100% natural rubber.  Rubber can be a bit heavier to tote around in a dive bag than the plastics used for most fins but the comfort, flexibility and responsiveness while diving can't be beat.  15 years and 9 awards later, no other fin has beaten the consistently high scores recorded by Scuba Lab, Scuba Diving Magazine and Scuba Gear Reports.

Ergonomic Design Apollo Bio Fins are designed with a 20º angle to accommodate a diver's natural tendency to bend slightly at the ankle and knee.  The angle is crucial to top performance and comfort.  The result is maximum propulsion with the least amount of stress on the body.  Apollo's choice of superior material and intelligent design provide divers with quick acceleration and the ultimate in power, speed and control.


Kicking It Wider kicks result in loss of momentum. Whether your cruising along or powering through current keep your kicks small.


Tips Avoid UV and other protective sprays and lubricants.  These products are often suitable for use with synthetic rubber but contain oils that damage Natural Rubber.  To keep spring strap hardware cosmetically appealing and easy to service, occasionally remove the screws for a quick brush.  If necessary, add a bit of baking soda for more thorough scrub.

Size Chart:  Bio Fin Pro C-Series (Spring Strap)


XS (X-Small) US Mens 6 ~ 7, Womens 5 ~ 7

Colors:  Pink, Blue, Yellow

Length:  504 mm, Width:  210 mm, Weight:  2180 g

Fit 3mm Boots:  ~ 24 cm

Fit 5mm Boots:  ~ 23 cm


S (Small) US Mens 7 ~ 8, Womens 7 ~ 8

Colors:  Black, Blue, Orange, Yellow, Pink

Length:  536 mm, Width:  222 mm, Weight:  2480 g

Fit 3mm Boots:  23 ~ 24 cm

Fit 5mm Boots:  24 ~ 26 cm


M (Medium) US Mens 8 ~ 9, Womens 9 ~ 10

Colors:  Black, Blue, Orange, Yellow, Pink, XT

Length:  560 mm, Width:  234 mm, Weight:  2930 g

Fit 3mm Boots:  24 ~ 27 cm

Fit 5mm Boots:  26 ~ 28 cm


L (Large) US Mens 9 ~ 11, Womens 10 ~ 11

Colors:  Black, Blue, Orange, Yellow

Length:  560 mm, Width:  234 mm, Weight:  3080 g

Fit 3mm Boots:  26 ~ 29 cm

Fit 5mm Boots:  27 ~ 30 cm


LL (Large-Large) 11W+

Colors:  Size LL Retired

Length:  560 mm, Width:  234 mm, Weight:  3080 g

Wearing LL?  Check Size marked on back of fin (L, LL or XL).  Compare foot pockets.  Transition from L to LL is partial size with just few mm increase in height and width of pocket. XL is a full size up with significantly wider foot pocket than LL.


XL (Extra Large) NEW Size 12 ~ 14

Colors:  Black

Length:  585 mm, Width:  234 mm, Weight:  3130 g

Fit 5mm Boots:  29 cm ~


Weight and dimensions are approximate.  Actual fit may vary.  US Mens & Womens recommendation based on use of 5 mm boot with average sole.  If you are in between sizes and have a wider foot or thicker soled boot we recommend selecting the larger size.  If you are in between sizes and have a narrow foot or thinner boot we recommend selecting the smaller size.  Rubber strap is fully adjustable and will provide maximum range of fit per size.


Apollo Dry Suits are sold with 5mm Boots 24 - 31 cm.


Customize Fit:  C-series fins are stocked and offered with a specific spring strap length. For example, size L is offered with a 300 mm spring.  If you prefer a more customized fit, springs are available to purchase separately 250, 275, 300, 325 & 350 mm.  See Fin Parts for more info.

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