By train
From Sannomiya or Shin-Kobe Station, take the subway to Tanigami Station (10-15 minutes, 4-5 departures per hour). Then, take the Shintetsu Arima-Sanda Line to Arima-guchi and transfer to the Arima Line to Arima Onsen Station (20 minutes, 4 departures per hour). The entire journey takes 30-40 minutes and costs 720 yen from Shin-Kobe and 900 yen from Sannomiya Station.
By direct bus from Kobe
Hankyu and Shinki Bus operate local buses from Sannomiya Station (50 minutes) via Shin-Kobe Station (35 minutes) to Arima Onsen. The one way trip costs 680 yen and buses depart once or twice an hour. Alternatively, Nishinihon JR Bus operates about seven highway buses per day from Shin-Kobe Station (50 minutes) via Sannomiya Station (30 minutes) to Arima Onsen. The one way trip costs 750 yen, while a round trip ticket is available for 1400 yen.
By direct bus from Osaka
Hankyu Bus and Nishinihon JR Bus operate one or two highway buses per hour from Hankyu Umeda Station or JR Osaka Station (60 minutes, 1330 yen) via Shin-Osaka Station (50 minutes, 1200 yen) to Arima Onsen. Nishinihon JR Bus offers round trip tickets for 2400 yen and 2200 yen respectively.
By cablecar and ropeway via Mount Rokko
From Sannomiya Station, take the Hankyu Kobe Line to Rokko Station (7 minutes, 180 yen), from where it is a ten minute, 200 yen bus ride by Kobe City Bus number 16 to the base station of the Rokko Cablecar.
The cablecar ride up the mountain takes ten minutes and costs 570 yen one way or 1000 yen for a round trip ticket. From the top station, take the circular bus line to the top station of the Rokko Arima Ropeway (ten 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, you can save some money by using the "Rokko Arima Katamichi Joshaken" ticket, which includes a one way ride on the cablecar and ropeway plus unlimited use of the circular bus line on Mount Rokko for 1700 yen.
How to get to and around Kobe