**The closely contested August 29 referendum on resuming EU accession negotiations, with recent polls showing yes support at 48–51% versus 48–52% no and several points still undecided, drives expectations for moderate-to-high turnout.** Iceland’s recent national votes have posted 80%+ participation, yet single-issue referendums have varied widely (49–75% historically). The narrow margin, focus on fisheries sovereignty and economic ties, and government framing as a “now or never” mandate increase mobilization incentives for both camps. Traders assign the highest implied probability to the 45–50% band, followed by 65–70% and 70–75%, reflecting uncertainty over whether the issue’s salience will match general-election levels or produce more typical referendum abstention. No major late developments have shifted these dynamics in the final days.