Officials say the seal pup has come onto the sand at the end of Collins Avenue for the last several days.
The Marine Education Research and Rehabilitation Institute says they will be monitoring the seal throughout the day.
But they believe it is just coming onto the beach to rest and is not injured.
They say everyone should keep their distance from it and make sure any dogs walking nearby are leashed.
MERR issued a statement that reads in part:
"We are monitoring this seal on Dewey Beach. It is a gray seal pup at post-weanling stage. This is when they have recently been weaned by their moms and are trying to learn how to survive on their own.
It is also molting (shedding fur) a little bit, and they need to stay out of the water during this process.
It is normal for seals to come up on the beach to rest. Many times they are fine and just need a place to sleep. In the case of a pup, just like a human baby, they need a lot of sleep. Unfortunately, this little guy decided to pick a beach that is very busy."
Anyone who spots a seal unattended by MERR is asked to contact the institute at 302-228-5029.