NOTE: I wrote this as preface to my Tampa report, but it got a bit long so I decided to put it in a separate post. It’s not really specific to Tampa, anyway.
What’s a marathon swim? Without any historical reference point (as for marathon runs), there are various definitions. The official FINA and (as of 2008) Olympic distance is 10K – which has the virtue of similar finish times as marathon runs. Penny Lee Dean sets the bar at 16 miles. Ted Erikson says 10 miles. Steven Munatones, as usual, wrote a nice overview of the issue.
I’m not really interested in debating what is or isn’t a marathon swim, though I do think:
- It must be in open water.
- It should be nearly impossible (or at least very difficult) to finish without refueling mid-swim.
- It should be very difficult to accomplish without support.
So, I’m fine with calling 10K a “marathon swim.” What about 24 miles, though? Typically, that’s described as an “ultra marathon swim.” My reason for discussing semantics here is, there’s something about a swim of that distance that’s not captured by merely adding the word “ultra.” A 24-mile swim is qualitatively (not just quantitatively) different than a 10K.
It’s different physiologically. In a 2-2.5 hour 10K, you’re still within the range of your pre-race glycogen stores (perhaps topped off with a couple mid-race feedings). Which means it’s possible to swim at near-threshold pace for the entire swim. In a 24-mile swim, you burn through not only your entire cache of muscle glycogen (perhaps 1,500 calories), but you’re burning through more calories per hour than you can possibly consume. Which means you must start metabolizing fat – a plentiful but less rapidly mobilized energy source – and swim at a substantially slower pace.
Even more important, a 24-mile swim is different psychologically. I’m thinking of two big issues here. First, failure is a distinct possibility, even for the best swimmers. Seasickness, digestive problems, hypothermia, tide changes — all can potentially end a swim. DNF’s happen in 10K’s, but as long as you’re a reasonably good swimmer and the water isn’t below about 16C, they’re pretty rare. In a 24-mile swim, you’re truly at the mercy of the swimming gods, no matter who you are.
Second, a swim this long is almost inevitably a struggle. There will be dark phases, and you can’t avoid them. You’re standing on the beach before the start, staring out at the water, and you know what’s coming. Maybe not the specifics of it… but you know there will be pain and doubt and frustration and possibly thoughts of giving up — but that you must try to push through them — to endure. This simply isn’t comparable to a 4-5 loop 10K (not to mention any pool race).
In any case, Tampa was my first ultra-marathon swim. I’ve never attempted anything like it; not even close. And the word “ultra” doesn’t quite communicate what a quantum leap it was.