Today I went to Santa Monica for a beach clean up, but I must have got the details wrong since I couldn’t find anyone there. No loss. The air felt nice. The ocean looked a little bit wild. My friend Jen and I picked a bit of trash here and there and waited out the traffic over beer and sweet potato french fries and talked about the writing life and our fathers who are both gone but who loom large in memory.

At home again, late with homework to do, I still wanted to do something about sharks. Since I’m going to South Africa, I decided to go donate Two Blocks of Sea to the great whites of Dyer Island, a rich nature reserve. The stretch of water between Dyer Island and nearby Geyser Rock (an island home to 60,000 Cape Fur Seals), is also called Shark Alley, a treacherous stretch of sea familiar to anyone who watches shows like “Air Jaws Apocalypse.”   I felt moved by the language of the donation form: 2 Blocks of Sea to the Great Whites of Dyer Island.

On a recent architecture tour in downtown L.A., the docent talked about a guy who purchased “air rights” so he could build skyscrapers. Air real estate. Two blocks of sea. I imagine some cut-away science text book diagram of green-blue water and a curved ocean floor.

Measuring the sea seems like trying to measure time. In November, my father will have been gone a year. But what does one year even mean? In a few minutes, I walk two blocks in a city that is both utterly foreign and oddly familiar. A thousand memory fragments surface and dissolve. Time is scrambled. What does a shark experience in two blocks of sea—the electromagnetic fields of distress, the rise and fall of tides?

Sharks don’t strike me as nostalgic creatures, but I wonder if they experience that confusion of memory when they move through some well-traveled stretch of open oceans only to discover it strewn with a ragged web of nets, or find a channel once plentiful with fish, strangely, suddenly empty.