Obama, wearing a checked shirt, khakis and sunglasses, was given a primer on the dam's operation by staff and he, in turn, asked several questions, including where the electrical power generated by the dam's hydroelectric generator goes.
Told it mostly goes to Southern California, Obama replied, "I always assumed Vegas got its power from here."
He also asked how long it took to build the dam and whether any workers died in the effort.
Asked by a reporter why he was visiting the dam, Obama said because "it's spectacular and I've never seen it before. I didn't realize it was so close by."
The president declined to respond to reporters' questions about his pre-debate preparations -- he goes head-to-head against his Republican rival, Mitt Romney, for the first time Wednesday in Denver.
Coinciding with the president's tourist outing, White House press secretary Jay Carney said during his daily briefing Obama issued an executive order directing the departments of State and Homeland Security to expand efforts to attract and welcome international visitors.
"A key element of the president's travel and tourism strategy is the visa waiver program, which allows eligible passport holders from 36 countries to travel to the U.S. without a visa for visits up to 90 days for tourism or business purposes," Carney said "This is a program for those foreign partners who meet the highest security and immigration standards."
Obama campaign spokeswoman Jen Psaki noted a New York Times report that Romney has benefited financially from his offshore holdings and tax shelters in Bermuda, the Cayman Islands and elsewhere, something she said "Romney has been telling all of you for months that he has not."
"This raises a lot of questions that the Romney campaign should have to answer -- he should have to answer tomorrow evening," she said. "We look forward to hearing what he has to say."
She said the Obama campaign isn't suggesting Romney broke any laws but it shows the need for tax reform, "and it raises the question to people who will be watching at home tomorrow night why they're paying a higher rate than one of the presidential candidates."
She also hit Romney on his healthcare plan, saying The Commonwealth Fund reported 72 million people would be uninsured under it.
"I believe that's more people than are uninsured now. So basically, his slogan is 'make things worse for healthcare across America,'" Psaki said.
Follow us on Twitter at @UPIDebates for complete UPI.com coverage of the 2012 Presidential Debates.