Good one this I'd be interested if anyone can come up with any links to real thermofluid tests etc for the theory behind split fins versus traditional.

I use mares volo race myself full foot for warm waters, less drag, and they work very nice. I would like to trim them with polystyrene floats to lift myself more horizontal though.

The only peer reviewed scientific studies that I have read actually state the the "Best Fin" tested have been

1) Jets
2) Apollo Bio-Fins with the split taped shut
3) Mares Attack
4) Apollo Bio-Fins

This recent (2003) study did not include ForceFins. A study completed some 10 years prior showed that they effeciency of ForceFins exceeded that of the Jets, unfortunatly that test was paid for by the Navy and they classified the data so its not available for everyone to read. They did this because it "would provide significant advantage" in the retail market.

Personally, I don't use splits and I don't worry about it

Well, no test studies to spout, just my opinion, but I am crazy about my Apollo bio fins. Add the steel springs! Recently was at Wolf in the Galapagos. All trying to catch up with a giant manta at a leisurely pace over lava reef until he turned and headed out over shoals. I blew past everyone and was the only one to get there as another manta passed. I was the only one of 16 divers with Apollos. I don't usually have the need for speed, but when I do, wow are these fins fast. I have found them amazing against strong currents in the Galapagos, too. Love them! Recently tried to use a pair of paddles again and just couldn't.

I agree about the Apollo Bio-Fins ... If the need is speed and power, the bio-fin is #1 ... I have even used them to scoop up a struggling diver in a current dive and move them forward when their own fins wouldn't give them any traction.

If you are frog kicking is areas that silt up easy, you had best practice alot before try your Bio's there as they can easy churn up a cloud is you kick even a hair too hard.

All in all, at about $200 USD, the Bio-Fin with the spring straps are worth every penny.

Oh the Apollo bio-fins look like the Oceanic V8 or v16 i cant remember the exact model. I was thinking about getting the oceanic ones lol! But now torn between them and the scubapro twin jet fins.