A Memoir of Exploring Light and Life in the Deep Sea

Edith Widder’s childhood dream of becoming a marine biologist was almost derailed in college, when complications from a surgery gone wrong caused temporary blindness. A new reality of shifting shadows drew her fascination to the power of light—as well as the importance of optimism.


As her vision cleared, Widder found the intersection of her two passions in oceanic bioluminescence, a little-explored scientific field within Earth’s last great unknown frontier: the deep ocean. With little promise of funding or employment, she leaped at the first opportunity to train as a submersible pilot and dove into the darkness.

Widder’s first journey into the deep ocean, in a diving suit that resembled a suit of armor, took her to a depth of eight hundred feet. She turned off the lights and witnessed breathtaking underwater fireworks: explosions of bioluminescent activity. Concerns about her future career vanished. She only wanted to know one thing: Why was there so much light down there?

Below the Edge of Darkness takes readers deep into our planet’s oceans as Widder pursues her questions about one of the most important and widely used forms of communication in nature. In the process, she reveals hidden worlds and a dazzling menagerie of behaviors and animals, from microbes to leviathans, many never before seen or, like the legendary giant squid, never before filmed in their deep-sea lairs. Alongside Widder, we experience life-and-death equipment malfunctions and witness breakthroughs in technology and understanding, all set against a growing awareness of the deteriorating health of our largest and least understood ecosystem.

A thrilling adventure story as well as a scientific revelation, Below the Edge of Darkness reckons with the complicated and sometimes dangerous realities of exploration. Widder shows us how when we push our boundaries and expand our worlds, discovery and wonder follow. These are the ultimate keys to the ocean’s salvation—and thus to our future on this planet.

There have been previous such expeditions – all failures. This time was different. There were many factors that came together to make this effort such a resounding success. One of these was a new approach to deep ocean exploration that pays heed to the natural visual environment of the vast midwater realm that is home to these leviathans. This is a world of the very dimmest of lights – both sunlight filtered through hundreds of meters of ocean and – bioluminescence – the living light that animals use to aid their survival in a light-limited world. The enormous eye of the giant squid – the largest in the animal kingdom – attests to how important vision must be to its survival. The teams’ use of optical lures that imitate bioluminescence to attract the squid and far red light invisible to the squid in order to see without being seen proved to be the key to success.

Below the Edge of Darkness, A Memoir of Exploring Light and Life in the Deep Sea: Order here

For speaking engagements and interview requests, please contact Lauren Tracy