Tomakomai is the junction point for the JR Muroran, Hidaka and Chitose lines. The trip from Sapporo, via Chitose airport, takes about 45-60 min depending on train type.
Tomakomai is best known as a major port, with shipping services to points throughout Honshu. There are two separate terminals, both served by local buses from JR Tomakomai station (~20 min to either) and by long-distance buses direct from Sapporo (around 1:30).
Kawasaki Kinkai Kisen (川崎近海汽船) "Silver Ferry" to Hachinohe, 4x/day
Shosen Mitsui Ferry (商船三井フェリー) "Sunflower" to Oarai, 2x/day
Taiheiyo Ferry (太平洋フェリ) to Sendai (daily) and Nagoya (3-4x/week)
Tomakomai-ko East Ferry Terminal (苫小牧東港周文フェリーターミナル). This terminal is home for Shin-Nihonkai Ferry.(42.609801,141.819742)
Shin-Nihonkai Ferry Tomakomai Terminal (新日本海フェリー苫小牧東ターミナル), Hamaatsuma 17-6, Atsuma, ☎ +81 0145 28-2800, . This ferry has lines connecting daily to Tsuruga and Akita, and to Niigata 3 times a week.(42.609801,141.819742)