Kushimoto

The following towns can be easily explored as day trips from Kushimoto:

Hongu
本宮町 Hongū-chō - Small town with an important religious history and ancient hot springs. Home of Hongu Taisha Grand Shrine mentioned above. (http://www.tb-kumano.jp/e...)
Kozagawa
古座川町 Kozagawa-chō - As the name suggests, this town centers around the Koza River. Lots of beautiful scenery and home of Shichi-kawa Dam.
Nachi-Katsuura
那智勝浦町 Nachikatsuura-chō - Home of Nachi Falls one of the tallest waterfalls in Japan, Nachi Taisha Grand Shrine, the Urashima Hotel pseudo hot springs "theme park", and a big tuna market.
Shingu
新宮市 Shingū-shi - Though a "city" by political defitions, still maintains a small town charm. Biggest selection of movie theaters, restaurants, and shopping in the extreme south. Home of Hayatama Taisha Grand Shrine mentioned above.
Susami
すさみ町 Susami-chō - Quaint little town that has the world's only undersea mailbox.