Specifically refers to passengers traveling by ship or boat, not by train or plane.
このフェリーは一度に500人の船客を運べる。
This ferry can carry 500 passengers at a time.
船客の多
Many of the passengers were enjoying the view on the deck.
Compound of 船 (ship) and 客 (guest, customer), literally 'ship guest'. The reading is on'yomi.