The picturesque town of Arima located on the other side of Mount Rokko from Kobe is a great place to explore the onsen culture of Japan. A nice day trip involving hiking is to go over Rokko and make your way down to the resort for a well earned soak in the famous Gin or Kin onsens (both of these are owned by the city and are the cheapest option but dont offer much in the way of facilities for your post bath chill out).
There are also many other hotels and spas which you can visit as a guest without having to stay in the hotel. Just stroll in and the rates for the baths will be posted on the ubiquitous vending machines in the lobby.
If you fancy spending the night then check out the list of hotels in Arima and make your booking online. Holidays and weekends will of course be more expensive and crowded.
By Train from Kobe
From Sannomiya or Shin-Kobe Station, take the subway to Tanigami Station (10 minutes, 520 yen from Sannomiya; 8 minutes, 350 yen from Shin-Kobe). Then, take the Kobe Railways Arima Line to Arima Onsen Station with one transfer at Arimaguchi Station (15 minutes, 370 yen).
By Bus from Osaka or Kobe
Buses to Arima Onsen leave from Osaka Station (60 minutes, 1330 yen one way) and Shin-Osaka Station (50 minutes, 1200 yen) and from Shin-Kobe Station (50 minutes, 750 yen) and Sannomiya Bus Terminal (30 minutes, 750 yen).
By Cablecar and Ropeway via Mount Rokko
From Sannomiya Station, take the Hankyu Kobe Line to Rokko Station (7 minutes, 180 yen). From Rokko Station, take the Rokko Cablecar up to Mount Rokko (10 minutes, 570 yen one way, 1000 yen round trip).
From the cablecar’s top station, take the circular bus line to the top station of the Rokko Arima Ropeway (10 minutes, 250 yen), which brings you down to Arima Onsen (12 minutes, 980 yen one way, 1770 yen round trip).
If you access Arima Onsen via Mount Rokko, make sure to purchase the “Rokko Arima Katamichi Joshaken” ticket, which provides a one way trip between Rokko Station and Arima Onsen using cablecar, bus and ropeway plus unlimited use of the circular bus line on Mount Rokko for 1700 yen.