Season
A rainy day
When the sites stay outdoors, the towns hold the museums. Constanța and Tulcea have enough interiors for a full day, if you check hours on the sheet or the institution's site. "Open now" appears only where we have checked hours - otherwise, phone.
Constanța, a wet day
MINAC, the Mosaic Building, the Art Museum, the Aquarium, the Natural Sciences Complex / planetarium. The peninsula has cafés and short cover between buildings. The seafront in rain is beautiful for ten minutes and cold after twenty.
Tulcea
The science and art museums, a covered harbour, a soup. Do not force a boat into autumn wind and rain just to say you have been in the Delta. Tomorrow may be better.
Mangalia and the south
The Callatis museum, the mosque (etiquette, not a group shelter), a café interior. Off-season many terraces close - the town remains.
What rain does not replace
Histria in a downpour is mud and slippery stone. Măcin is dangerous wet. The Delta in a storm is not "dramatic", it is a mistake. Stay in town.
Kit
A thin rain jacket in the pack, all year. Shoes that dry. An offline map - the signal does not improve when it rains.