Ive got 2 of these units, 1 on my walleye boat, and 1 on my lake mich. boat.my walleye boat has lake chip in it ,it shows contours anddepth changes you can even set it up to display color changes by depth.very detailed,you wont learne it all in first trip out but very worthwhile.plus the gps function wil get you back home every night.