Nautical charts and tidal data
Option 1: Purchase a nautical chart to a destination your favorite paddler longs to go.
Option 2: Buy Chart No. 1, the guide to nautical abbreviations and terms.
Option 3: Buy the AyeTides ap (for paddlers with iPhones), which provides buoy data on tides and currents at thousands of locations around the globe.
Option 4: Photocopy a portion of a chart and laminate it to create a waterproof deck chart. Include a grease pencil for taking notes on the chart.
Option 5: (Best of all...) Treat your favorite paddler to all four!