A man visiting Ding Dong Dell is rather flustered after misplacing his diary.
This errand is available to complete after defeating Hickory Dock in Ding Dong Well.
To begin this errand, talk to the traveler standing just outside of the Cat's Cradle in Ding Dong Dell, and he'll tell you that he keeps his journey recorded in his diary, but he can't seem to find it. Agree to help, then head out to the World Map to find it.
He said he sat down beside the river northwest of Ding Dong Dell, on an island with a couple of trees. If you look at your map, you should see it; it's on the corner of the stream to your north-northwest, just south of the large lake to the far north. There's a skeleton nearby to the west-northwest. Make your way to that island and examine the ground near the trees to find the traveler's diary.
Return the diary to the traveler and you'll complete the errand.