From the publisher:
The Swallows and their father, Navy Commander Ted Walker, planned a camping trip but father was called away on naval business. Instead of camping, Father sets them a challenge: use a dingy to explore and create a map of low-lying islands until he can return.
As the children explore the inlets, coves, mudflats, and estuaries, they end up in a friendly "war" with The Eels just as Bridget, Titty, and Roger are trapped in the middle of a ford by a rising tide.
