In Costa Rica, voting is underway for the first round of the presidential election after a campaign dominated by same-sex marriage. <br/><br/>A total 13 candidates are vying to succeed outgoing President Luis Guillermo Solis, who is constitutionally barred from seeking a second consecutive term. <br/><br/>Same-sex marriage is seen as a key issue in the socially conservative Central American country, where 3.3 million voters are eligible to cast ballots.