Let p≥3 be a positive integer and let k∈1,2,...,p−1⌊p/2⌋. The generalized Petersen graph GP(p,k) has its vertex and edge set as V(GP(p,k))={ui:i∈Zp}∪{ui′:i∈Zp} and E(GP(p,k))={uiui+1:i∈Zp}∪{ui′ui+k′∈Zp}∪{uiui′:i∈Zp}. In this paper we probe its spectrum and determine the Estrada index, Laplacian Estrada index, signless Laplacian Estrada index, normalized Laplacian Estrada index, and energy of a graph. While obtaining some interesting results, we also provide relevant background and problems