Swimming to Antarctica by Lynne Cox. Very inspiring! Lots of adventure.

The tales of her training and experiences in long distance, open water swims all around the world. Sounds a little dry, but I found it fascinating, gripping, and inspiring.

Polar Dream by Helen Thayer. Also very inspiring and nothing but adventure.

I haven't read this for a long time, but I remember finding it utterly gripping and fascinating. A woman Xcountry skis alone to the North Pole (I think). She encounters all kinds of challenge, as you might imagine, including Polar Bears!! Also very inspiring.