with the results that you're getting out of the stock 9-inch coil so far, there isn't any reason you won't have success with it in lakes and parks. It is a great all around coil and does well on coins and jewelry. If you want to cover more ground with each swath, consider a larger coil. But keep in mind that target separation isn't as good with large coils, compared to smaller coils. And if you're hunting in water, know that the only large waterproof coil currently available is the Coiltek 15-inch DD. If you want extremely good separation, consider the 6-inch DD at 18.75 kHz. The higher frequency is super sensitive to low conductive targets, such as gold and small jewelry. And it has surprising depth. JMHO HH Randy
BarnacleBill ----Size does matter - - - Coil selection
http://www.findmall.com/read.php?55,745158,745158#msg-745158
Digger - information from Minelab USA - X-Terra coils, waterproof or water resistant?
http://www.findmall.com/read.php?55,1068029,1068029#msg-1068029
Coiltek 15-inch DD All Terrain X-TERRA coil at 7.5 kHz
http://coiltekmanufacturing.com.au/x-terra.html