My question is that whether working/job on Cruise Ships is allowed or not?
(1) Cruise ships have bars and casinos, so if someone works as part of management of the ship not specifically of the bars or casinos, so can working be allowed and income is halal?
(2) Chances are that Jumuah prayers will be missed for several weeks or even months, so in this case working is allowed or not?
(1) If you do your job keeping yourself away from wine and gambling then in the above mentioned case it is allowable. In this case your income shall not be termed as haram rather it shall be halal.
(2) If you miss Jumuah because your ship is in such a place where Jumuah is not valid then you will not deserve the warning of missing Jumuah. Yes, if your ship has cast anchor at seaport which is situated at the city or big town and you have the facility to offer Jumuah salah and yet you miss Jumuah salah then you shall deserve the warning. Though in this case your income and salary shall not be termed as haram but you shall be sinful for missing Jumuah salah.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband