It's important, first of all, that your craft be a canoe, ash-ribbed and canvas-covered (never aluminum -- and rowboats won't do because their oars cast double sweeps of swirl and shadow). Noon's best, when the sun's stroke is vertical as your thin paddle finning water toward the scored bumps strung out in knots on their watered log. Eventually, of course, they'll sense your drift across their lily pads and sound off one-after-another like flat grenades. So then, with nothing to lose -- a last churning stroke, ship paddle, crouch to the gunwale, wait. And when a lemon-striped blunt head pokes up through milfoil, make a grab for what's unseen. You come up with a handful of weed and a turtle the size of a twin-yolked chestnut, its legs and head drawn snug inside a double plated shell draped green. Turn it over, and the under side's its own mirrored pattern -- pale blue and rose and cream. Now make it yours: Lower it level, just your fingertips on the rim, till pond water laps all edges. Then the catch will accept you, extend itself -- and swim.