His father, Shannon Griffith, the football coach at Division III Manchester University, said via Twitter that his son was in an accident "involving a rip current."
"My wife, Kim, and I have been at Isaac's bedside since 2 AM we are encouraged with his progress in ICU but we have small battles to face and are asking for your thoughts and prayers," Shannon Griffith said early Tuesday morning in a series of tweets after flying to Sarasota to be by his son's bedside. "His vitals are stable but we still need for continue prayer for his lungs."
The father said his son was still on a ventilator.
The Sarasota County Sheriff's Department said Griffith was drinking in a hotel room with fellow players Nick Stoner and Ty Smith and a friend, Mitch McCune, when the four decided to go swimming at Siesta Beach.
The current swept all four away from shore, authorities said. When the 19-year-old Griffith went under, he was rescued and returned to shore unconscious by McCune, who performed CPR until sheriff's officers and emergency units arrived.
Sarasota Memorial Hospital spokeswoman Kim Savage says the family has requested privacy. A police report says Griffith's CT scans were normal and spokeswoman Wendy Rose says Griffith's "signs are positive."
The school released a statement saying: "We are aware of Isaac Griffith's condition. Our prayers are with Isaac and his family and we ask Hoosier Nation to keep the Griffith family in their thoughts."
The Fort Wayne native verbally committed to the Hoosiers in June 2012.
The Associated Press contributed to this report.