Among the roughly 4,000 people stuck onboard the stranded Carnival Triumph are Cristi Presley and 90-year-old Alicia Ancira, the sister and grandmother of April Ancira.
The Anciras are well-known to San Antonio as a family that owns several local car dealerships.
So far, the Anciras have not been able to reach their loved ones by phone.
"I tried to call my grandmother before talking to you guys, but it went to voicemail," said April. "We don't know what's going on as far as they're concerned."
The ship lost power Sunday off the coast of the Yucatan Peninsula after an engine fire.
Although the cruise was supposed to arrive in Galveston on Monday, a tug boat is now pulling the ship to Mobile, Ala., where it is expected to dock on Valentine's Day.
Passengers and crew have no power and no running water. Toilets are said to be overflowing and sewage is spilling into hallways.
Other relatives of San Antonians stuck onboard tell KSAT 12 News that passengers are relieving themselves in plastic bags and that the foul odor is making people physically ill.
The conditions are concerning for anyone, but especially for April's elderly grandmother.
"I would hate to find out that she has a health condition pop up and there is nothing they can do, no emergency units that can get there quickly," she said.
The National Transportation Safety Board and U.S. Coast Guard announced Tuesday that investigators will be sent to Mobile to determine what went wrong.
