One piece, vol. 15, paperback/eiichiro oda

Namis sickNow the Merry Go is without her navigatorLuffy and crew have but one choice--find land and hopefully a doctor.

They miraculously stumble upon Drum Island where it is eternally winter, but upon arriving they find out the island has only one doctor--and shes a witchWith Namis life on the line, Luffy sets out through the snow-laden fields to find this doctor, witch or not.