The cable is expected to vastly improve government and state company efficiency and open the way for a relative boom in online business.
"The company is going to benefit a lot. It will represent a huge savings in time and money and make our work much easier," Moraime Rodriguez, chief accountant at a state firm, said.
Young Cubans looking to leave the island often cite poor communications and isolation from modernity as a reason.
"At last we will have a good and less expensive connection to the world," 30-year-old computer technician Yurislaidi gushed in an interview from Chile, where she moved a few years ago to learn more about her profession after becoming frustrated with the technology and limited Internet access available in Cuba.
"If only this will allow Internet to arrive in Cuban homes as I think it is the only place in the world without this service," she said.
According to local officials Yurislaidi's wish will not be fulfilled any time soon.
Deputy Communications Minister Jorge Luis Perdomo warned this week the cable was not a "magic solution" and to get most Cubans online would involve large investments in infrastructure.
Perdomo insisted there were no "political obstacles" to Internet use, just economic, but implied for most Cubans getting connected was still a long way off.
His was just the latest of a series of official statements aimed at dampening public expectations.
"The underwater cable will provide higher quality communications, but not necessarily mean a broader extension of the same," the Communist party daily Granma warned late last year.
Granma pined that priority would go to those already with access. In other words, broad band will debut for the government, state and foreign companies, tourists, some Cuban professionals and those who buy time at hotels or account numbers and passwords on the black market.