I give it to Deidara as well.
Location is just a tremendous advantage for Deidara because the water compresses Deidara's explosives, bolstering their power as a result. Unfortunately for Jiraiya, the bulk of his guerilla tactics do stem from employing underwater strategies, so scattering copious amounts of bombs underwater would render many of Jiraiya's strategies useless. Jiraiya is simply ill-suited in handling Deidara without Sage Mode and Deidara's repertoire enables him to seize control over the air, bridge, and water, so I don't see Jiraiya doing anything. He eventually gets bombarded by Deidara's explosions.