The Secret World of Seahorses by Nicola Davies, illustrated by Lou Baker-Smith (Candlewick, 32 pages, grades K-4). This straightforward introduction to seahorses includes information on eating, mating, reproduction, and body structure. Human activity endangers millions of seahorses–76 million are caught every year and turned into lucky charms, key rings, teas, and tonics. Three projects to save seahorses around the world are described, in Malaysia, Cambodia, and England. Additional information about seahorses and climate change is given at the end.

This would make a great nonfiction companion to Eric Carle’s Mister Seahorse, offering more information about different aspects of seahorses that are touched on in that book. The mixed media illustrations with a wide color palette do a beautiful job of portraying underwater scenes. While Nicola Davies doesn’t shy away from describing human dangers to seahorses, the specific projects to save them add an upbeat note.

If You Went to the Bottom of the Ocean by Brooke McIntyre, illustrated by Gordy Wright (Chronicle Books, 50 pages, grades 1-5). Follow a submersible as it heads out into the ocean, then dives down, down, down. In the sunlight zone, there’s still plenty of light and life, but as you head through the twilight zone and the midnight zone, there is less and less of both. It gets colder and darker, with the weight of the water pressing down harder. Finally, 3.5 miles down, you’ll reach the floor of the ocean…but there are still more depths to explore. The Mariana Trench is another 3 miles deeper, and if you reach the bottom, you’ll be in a place few other humans have ever seen. Includes additional information about the layers of the ocean, their geography, and milestones in human exploration.

Both the writing and the illustrations do an amazing job of conveying the vastness and wonder of the ocean depths. The illustrations grow darker and darker, illuminated by the bioluminescent creatures that live there. The back matter adds interesting information and may inspire readers to dream about traveling to a part of Earth that is still 90% unexplored.