I got on a pontoon pushed by a ship from Calarasi, Romania, crossing the Danube / border to Silistra, Bulgaria.
Staying overnight in Silistra, I visited the Srebarna Nature Reserve WHS by bus. The sign at the bus stop for Bus 22 (located at 44°06'49.4"N 27°15'10.8"E) says it runs from 5:15 on but does not say exactly what time. So instead of milling around waiting for the bus at the bus stop, I decided to take another bus from the main bus station a few hundred meters away to the city of Ruse at 9:30 and get off at the entrance to the village of Srebarna.
As soon as I got off the bus at the entrance, an old lady who also got out of the bus just waved to the first car she saw to get a ride into the village, and I was at the visitor center/museum for the WHS in no time.
I first checked out the museum and then walked out to the lake. There were two groups of pelicans nesting in different shores of the lake.
This site is just one lake, so it wasn't as extraordinary and impressive as the Danube Delta.