It's time to welcome the summer boating fun.

But with the excitement of the lake comes some danger as the lake levels stay low.

To keep your fun from running aground, adding a global positioning system to your boat will help you navigate the shallow waters and help avoid under water dangers.

"I think they (GPS) would be very good for people that don't know the lake very well," said Bill Vanderford, fishing guide on Lake Lanier and a member of the National Freshwater Fishing Hall of Fame. "For someone like me that has been guiding for over 35 years, I know where everything is; for people that are learning to get around out there it would do them good to get out there and drive around slowly and see the things that are out there."

Vanderford said the GPS satellites have been an important part of his fishing equipment for years.

"Most of our depth finders, sonar units, whatever, has GPS built into them," he said. "We use them a lot at certain times of the year, not so much in the springtime, but we use it a lot to find underwater structures. Sometimes when we are in fog we use it to navigate out there."

Finding and marking the underwater structures and obstacles is important, but GPS systems can also show the depth, shoreline and certain locations.

"(GPS) will actually show the shoreline, the depth contours and the GPS points," said Len Jernigan, general manager at Aqualand Marina in Flowery Branch. "Depth finders can be inexpensive, they can be less than $100 and a GPS can be under $200. The thing about a depth finder is it doesn't show what is in front of you.

"Your depth finder is going to tell you that you are on the bottom just after you hit bottom."

Although, GPS cannot show you trees or other obstacles hidden in shallow water, Jernigan said.

The navigation units range from around $100 to thousands, but Wink Porterfield, inventory manager at West Marine in Buford and member of the Lake Lanier Sailing Club, said many customers find what they need for a few hundred dollars.

"The general price range that people seem to be buying in for our customer base, the walk-in customers, tend to be buying in the range of $400 to $800, very few spending over $1,000," he said. "The capability of these machines today is unbelievable ... it's actually more accurate in terms of positioning than a 1970s-era ballistic submarine."

Porterfield said there are four major brands of GPS: Garmin, Lowrance, Raymarine and Hummingbird. The Garmin 530, for example, sells for about $750 to $800 and comes loaded with detailed maps for U.S. inland lakes, including 5,300 lakes with shoreline and depth contours and navaids, according to garmin.com.

"If they absolutely are going to spend their time on one lake ... they may know the lake so well that they don't need a GPS," he said. "If they travel to different lakes, they may want a GPS that also has a chartplotter.

"That is an important word because then it not only tells you where you are but it shows you where you are on a map. GPS shows you where you are in the universe."

Along with a chartplotter, Porterfield said another great feature is how the GPS can record waypoints, which are points on a body of water.

"Any GPS can record, usually the minimum is up to 500 waypoints, which are places to remember," he said. "Most GPS will remember accurately within 10 feet, give or take, and any time you can come back to that spot."

The GPS will remember a string of waypoints and also how you got there and came back, Porterfield said. "Also, you can tell the GPS how much water your boat requires and it guides you along that path."

Along with chartplotter GPS, marine specialty companies also offer products like sounders, fishfinders, handhelds, radar and autopilot versions.

For Jernigan, GPS is important for marine navigation but he wants people to remember to use common sense.

"There is still plenty of lake out there to use ... it's the same navigational issues here as they have on the coast, we just aren't used to dealing with it here," he said.

Vanderford joked that lower lake levels were great for fishing because it concentrated the fish. But he did think GPS could help with your big catch.

"They help you find the fish, in that you have to find the structures that they are in," he said. "What we have done, when we have found those structures, we've marked them on the GPS permanently and we can go back to them very easily.

"We mark it as an underwater structure with fishing in mind, not necessarily safety in mind."