Riomar [cat. Riumar] is located at the Spanish Costa Dorada, round about 180km to the south of Barcelona. It is in the middle of the Ebro Delta nature reserve, the second largest of Spain and still one of the largest in the Mediterranean sea. The region is famous for its rice cultivation. The urbanization Riomar belongs to the city of Deltebre (8km away).

In Riomar most of the houses are privately owned  and detached or semidetatched. There are two hotels, two camping sites, a bakery, a smale supermarket and a variety of restaurants and beach bars. You will also find a shop for fishing equipment, papers- and souvenir shops.

Riumar is located in the Catalan part of Spain. Here "Catalan" is spoken. It's different in spelling and pronunciation to the "Kastelan", what we call "Spanish".

"Riumar" is "Catalan", "Riomar" is "Kastelan"

So, both is correct!

Just like Riumar:
"Costa Daurada" is katalan, "Costa Dorada" castilan.