No, it wasn't a diving trip. We didn't dive this time, but went to the volcano complex @2093 above sea level, where 'bintang' served in room temperature and 'indomie rebus' sold more expensive than 'nasi goreng special pake telor'.
Dieng Plateau located in Central Java, about 4 hours drive from Jogja. Wonosobo is the nearest city, most people stay in Wonosobo for better accommodation, but I recommend you to stay at Dieng. We stayed at Gunung Mas, near the Arjuna Complex. Very basic, but clean and staff are friendly (they charge you for hot shower though). Ibu Jono is the most popular homestay according to the travel guide book,but I think Gunung Mas is nicer and cleaner.
Came at rainy seasons was not fun, we missed the sunrise, and caught by rain during the day. But still, Dieng is pretty! Some pictures from the trip.