Tumbes is the capital of the Department of the same name in the Region Grau.
There are kombis to beach resorts, & colectivos to the frontier. Customs & immigration are several kilometres inside Peru & Ecuador so make sure it is understood that colectivo/kombi/taxis wait while formalities are concluded, & they do not drive off with your belongings on any unexpected diversions. International buses are a safer means of crossing the frontier. Beware of false currency exchange.
White sand beaches, mangroves, Tumbes River & National Parks like Amotape.