Tango-hantō is a peninsula that juts up into the Sea of Japan on the north coast of Kansai. The inside of the peninsula is covered with thick forest, idyllic mountain villages and babbling streams, while the serrated coast alternates between good sandy beaches and rocky points.
Takeno is a pleasant little fishing village and summer resort with two good sandy beaches: Benten-hama (弁天浜) to the west and Takeno-hama (竹野浜) to the east. To get to Benten-hama, exit Takeno Station and turn left at the first light and walk straight for about 15 minutes (you will cross one big street en route).
Amanohashidate (the Bridge to Heaven) is rated as one of Japan's 'three great views'. The 'bridge' is really a long, narrow, tree-covered (8000 pine trees!) sand spit, 3.5km in length. There is decent swimming, as well as beach showers, toilet facilities and covered rest areas, the length of the spit.
There's nothing overly appealing about the two ports of Nishi-Maizuru and Higashi-Maizuru, but they play an important part in the area's transport networks. If you've come from the west on the Kita-kinki Tango Tetsudō trains, Nishi-Maizuru is the end of the line and where the JR Obama line comes out to meet the coast.
Moroyose, in Hyōgo-ken, near the border with Tottori-ken, is a pleasant little seaside town with a decent sand beach. Youth Hostel Moroyose-sō is a good spot to stay for backpackers, with fairly large rooms for a YH and breakfast/dinner for ¥630/1050. It's a 10-minute climb uphill from the eastern end of the beach.