Sue and I are staying at the Gateway to Cape Cod and this area is supposedly the 3rd largest producer of cranberries (behind New Jersey Pine Barrens and Wisconson) and this weekend was the Cranberry Festival sponsored by Ocean Spray and only 10 to 12 miles from our campsite. Not only that, there was a large cranberry bog right at the entrance to our RV resort that I could monitor daily for the answers.
If the truth be known cranberries need to be grown in mostly dry soil, and not in a pond or lake, if the cranberries are underwater for to long they will drown and the fruit rot. The fields are flooded during harvest. The bogs are marked with flags to determine the water depth as it is pumped into the bog.
Once the bog is flooded the cranberry farmers drive through the flooded field or bog with a tractor like device that has a rotating device on it that knocks the cranberries loose from the plants.
Each cranberry has four air pockets in it which make it float to the top of the water, so that the guys from the ocean spray commercial can stand in a bog of cranberries and confuse you.
The bogs are immediately drained to protect the plants, and the plants are perennial and last indefinitely if cared for properly and protected from frost.
The festival was quite enjoyable, lots of displays on and info about ( you guessed it Cranberries ) You had a chance to try and/or buy cranberry muffins, cranberry vodka, cranberry candles, cranberry soap, cranberry etc... etc... etc... ( sounds berry much like a knock off of the Forrest Gump movie doesn't it.) The most interesting part was when we were bused back to a bog and got to see first hand each step in the process of flooding and harvesting.