The "Faithful Steward" sunk in 1785 and lost 430 barrels of coins. They still find a bunch, but usually after a Nor'easter hits. I go to the beach about every day. You can park at the Indian River Marina entrance, which is the Delaware Seashore State park, North side of the inlet, and walk under the bridge, then head north on the beach. They are building a new inlet bridge, so the traffic pattern is a little messed up. I live right on the bay there.
Make sure you only detect east of the dunes!!!!!! Crossing into the dune area is a huge no-no. If you drive onto the beach you need a beach tag and must be actively surf fishing. You can't just park out there. Conquest Rd. is also a good place to park and you can walk south towards the inlet. Rule of thumb when it comes to the state parks and the Rehoboth/Dewey/Bethany beaches is that, if you see life guards, then you must wait until after 5pm to detect. Believe me, they will make you leave the beach.
On Rt.1 about 2 miles south of "Seaside Country Store" (you can't miss it), Fenwick Island, there is the "Sea Shell City". Above that is the "Discovery Sea" museum. It's a great place to visit.
Hit the beach during low tide and get in the trough with your scoop. It drops off to neck deep and the waves are rough, but if you scoop a couple piles into a bucket, you'll find a couple neat things. Sea glass is a great find as well. I picked up about 5 conch shells the other day.
I've been finding a lot of metal lately. Very old, half dollar size chunks from something or other.
Have a fun time, it's beautiful out there.
Have a good time