Tom Christensen's excellent blog. Four years on, I'm still reading it.
Writing from Merida
By Canadian writer in Merida, Mexico, Joanna van der Gracht de Rosado. Mexico bloggers, be sure to add this one to your blogrolls!
Blue Ocean Notes
Dr Safina at TEDx in DC on the Gulf oil spill. (Fast forward 1: 38)
UGA Department of Marine Sciences blog.
Scientific American Expeditions Blog
Sic Semper Tyrannis
I've been following this one for several years now, especially when things get dicier than the usual extreme diciness in the Middle East.
See the note on McChrystal.
The Barefoot Beekeeper