Saulius Kvaraciejus, 20, vanished after he and two friends went rafting on Pennypack Creek around 6:00 p.m. Tuesday.
They began at Roosevelt Blvd. and made it to some rapids by Rhawn Street.
Kvaraciejus fell off his raft, surfaced a few times, then went under a final time and hasn't been seen since. His two friends made it to the shore.
Authorities say the water in that area was about 20 feet deep and very violent at the time.
The water level had gone down significantly since Kvaraciejus vanished.
Philadelphia police spent Wednesday morning searching the river and riding along its banks on dirt bikes, looking for any sign of Kvaraciejus.
On Tuesday morning, crews had to rescue another man trapped next to the pillar of a rail bridge that crosses the Pennypack Creek in the Holmesburg section of the city.
