[madhadron]

For diving mammals, most of the oxygen is carried in the muscles by myoglobin. It turns out that the myoglobin density in muscles is very precisely related with the diving ability of the mammal, and the the density is also very precisely correlated with the surface charge (and thus the exact sequence) of the myoglobin protein. There's an amazing paper about this that then uses myoglobin sequence to infer the diving abilities of extinct mammals.[1]

I'm not in general willing to be a guinea pig for genetic manipulation, but toothed whale myoglobin and being able to dive with empty lungs for half an hour or 45 minutes? Sign me up.

[1]: Mirceta, S., Signore, A. V., Burns, J. M., Cossins, A. R., Campbell, K. L., & Berenbrink, M. (2013). Evolution of mammalian diving capacity traced by myoglobin net surface charge. Science, 340(6138), 1234192–1234192. http://doi.org/10.1126/science.1234192