Every time I pick up the new book “;The Sea Sleuth: Edventures [sic] of a Marine Detective,”; by state Department of Land and Natural Resources biologist Dave Gulko, I crack up.

I also learn something each time, too. Today I learned how to decide, while out there on the wave-washed rocks, whether an opihi (limpet) is big enough to pick. On another page I spotted a little label in the corner of a busy picture that said, “;Recycled Kosher Dill Pickles.”; And I was laughing again.

This fantastically designed, solve-the-crime book is fun, but it's also challenging. Besides not knowing a lot of Hawaii's marine resource laws, and I thought I did, I didn't know how enforcement officers go about investigating possible marine crimes.

Dave tells us this in stories based on true events but with made-up names. In one, scuba diver Aila Vadiven (say it out loud) visited a cave off the Kona Coast and found the big school of resident menpachi (soldierfish) missing. Several dead cowries lay on the floor, some snail bodies still in their shells.

The suspicious diver brought the dead snails to officials who sent them to a lab. Based on the report—gills consistent with chemical burning—officers staked out the major boat harbors of the area, and two nights later arrested two men on their boat.

How did they solve “;The Case of the Cleaned-out Cowries”;?

This is one of the few I guessed right. The chemical burning was consistent with bleaching, and the men had swimming pool chlorine in their boat. They had the boat confiscated, spent seven months in jail and had to move away due to the fury of the local community.

I don't know whether the last sentence is all true, but it should be. Bleaching a reef is an appalling crime. Chlorine bleach stuns the fish and kills everything else in the area. After releasing bleach from a plastic bag, collectors catch the stunned fish easily, but they often die after they're sold.

That's a depressing story, but here's something to lighten the mood. When I looked carefully at the bungalow picture of a honeymoon couple, two of several suspects in a turtle-killing case, a pair of men's briefs are lying under the table, and a bikini is draped on the stove and fridge.

If that doesn't make you smile, peruse Dave's classified ad page under Businesses for Sale. “;Part-time Gold Mine!”; one ad says. “;Make $$$ 1st wk! Battery-powered sea slugs. Fun at parties. (411) 532-...”;

Also note the name of the plastic bottles of water sitting on several desks: Aquawater H20.

For this unique book ($12.95), we can thank Honolulu's Mutual Publishing, the National Science Foundation and lots of helpers from the University of Hawaii, including the high school lab students who tested case puzzles in their classrooms.

It's hard to find humor in sewage spills, molecular markers or gillnet regulations. But when Mr. R.U. Stenke runs the treatment plant, an instructor teaches class in scuba gear and cockatiels are peeking around unlikely corners, the subjects are a lot more fun.

Weeks after I got the book, I'm still paging through “;Sea Sleuth”; and still laughing and learning.

I don't pick opihi, but I can now tell those who do what to carry in their pockets when they go: a quarter. An opihi must be at least that size to legally take it.

I will also remind people to recycle their dill pickles.