All shellfishing requires a permit from the Town in which you will be harvesting. In addition, certain tools will make the harvest more rewarding. For quahogs (hard shell clams) a long-handled tool with curved tines at the base (with or without a basket) will allow the digger to stand and scratch the surface to a depth of six inches which is where the animals are to be found. For Steamer clams (soft shell) the tool is a short-handled hoe that has tines of about 12 inches in length. The digger uses this tool to dig a trench about 10 inches deep and uncover the clams. This tool may also be used for razor clams.
Oysters, scallops, and mussels do not burrow - they live on the surface and may be harvested by hand or using a quahog scratcher. When searching for these species underwater, be mindful of the fact that your activity will likely turn the water muddy - much of the technique uses the sense of feel.
Be sure to protect your feet with boots or old sneakers - broken shell fragments can inflict a serious cut. Hat, insect repellant, and sunscreen are also recommended.