Deep play (aka "Flow") is a valuable concept, but don't expect to find any intelligent exposition of it here. Instead, prepare for confusion as seemingly disparate phenomena -- rituals, hallucinations brought on by starvation, and Sunday morning reveries in the park -- are evinced as examples of "deep play". Just how and why these should be lumped together with creative flow is never adequately explained.
All in all, this is a rambling, entirely unsystematic and underresearched book, notwithstanding the author's credentials as a naturalist.* Worse still, as Wolfgang Pauli would say, it is "not even wrong". It has nothing to say, for page after page after page.
Well, not nothing exactly. As an indulgent exercise in vanity, it's worth a titter or two. The author, whose photo reveals a woman of a certain age in King Charles-style tresses, loses no opportunity to remind you the reader that she knows how to live. "I hate the fearful trimming of possibilities that age brings. If you lead a relatively narrow life, I suppose you never notice. But I've always been athletic"... etc etc. Mostly she goes on in this vein, larding up her exploits with new age musings that even I --liberal, female and eco-minded-- found eminently gagworthy. Reader be warned, though: a dark episode intrudes on page 100, as Ackerman takes NASA to task for having had the temerity to reject her for the Journalist in Space program. Her explanation: NASA feared she might say something "wise and profound."[!]
Whatever the case, don't hold your breath waiting for her to say it in this book.
*Serious readers of psychology would do better to consult Czikszentmihalyi's outstanding research on "Flow", while those interested in play in the natural world will adore Bernd Heinrich's Mind of the Raven.