  Three dimensional supersymmetric field theories have large moduli spaces of
circular Wilson loops preserving a fixed set of supercharges. We simplify
previous constructions of such Wilson loops and amend and clarify their
classification. For a generic quiver gauge theory we identify the moduli space
as a quotient of $C^m$ for some $m$ by an appropriate symmetry group. These
spaces are quiver varieties associated to a cover of the original quiver or a
subquiver thereof. This moduli space is generically singular and at the
singularities there are large degeneracies of operators which seem different,
but whose expectation values and correlation functions with all other gauge
invariant operators are identical. The formulation presented here, where the
Wilson loops are on $S^3$ or squashed $S^3_b$ also allows to directly implement
a localization procedure on these observables, which previously required an
indirect cohomological equivalence argument.
