I purchased the USA lakes for just $10. The first three days of fishing here on Lake Erie, I was fishing with some friends in their boats rather than my own and being able to carry the chart around in my pocket has been marvelous. The phone's GPS told me my location and the Navionics app. provided the chart and speed. I was able to mark spots while with my friends and when my son arrived to fish with me yesterday and today, I had areas marked which held fish. Great app, especially for the price.