Thermal-hydraulic　characteristics　under　ocean　conditions　are　significant　for　the　safety　and　reliability　of　nuclear　reactors.　A　large　amount　of　works　concerning　this　topic　have　been　done.　However,　many　of　them　are　mainly　for　dynamical　systems　in　submarine　and　ships.　With　the　development　of　floating　nuclear　power　plant　(FNPP)　which　purpose　is　providing　power　to　remote　area　or　ocean　platforms,　a　lot　of　more　works　need　to　perform.　The　difference　between　FNPP　and　dynamical　system　brings　new　challenges　to　researches　of　thermal-hydraulic　characteristics　in　nuclear　reactor　under　ocean　conditions.　This　paper　investigates　many　literatures　involving　the　ocean　motion　effect.　A　large　number　of　experimental　studies　on　natural　and　forced　circulation　under　ocean　conditions　are　based　on　tube　and　rectangular　channels.　The　effects　of　ocean　motions　on　friction,　flow　instability,　heat　transfer　and　critical　heat　flux　(CHF)　are　investigated　by　previous　researchers.　The　challenges　are　that,　first,　conclusions　obtained　from　simple　channel　can’t　always　extend　to　the　rod　bundle　channel.　Second,　studies　of　ocean　conditions,　always　using　one　or　two　dimensional　movements,　which　are　relatively　simple　and　cannot　reflect　the　complicated　ocean　environments.　Third,　there　are　lack　of　comparison　between　natural　frequency　of　two-phase　flow　instability　and　frequency　of　ocean　waves　which　may　cause　unwanted　problems　due　to　resonance　or　coupling　behaviors.　Forth,　CHF　experiments　that　performed　to　examine　the　ocean　condition　CHF　events　are　far　from　real　reactor　conditions　where　CHF　events　take　place　in　high　temperature　high　pressure　condition　under　complicated　three　dimensional　geometry　with　open　channel　environments,　sometimes　even　under　the　influence　of　mixing　vane　grids　(for　most　of　the　SMR　designs).　Last,　there　are　no　work　about　length　effect　and　mixing　effect　from　spacer　grids　which　make　thermal-hydraulic　characteristics　different　in　FNPP.　Many　codes　adopt　flow　and　heat　transfer　correlations　which　are　developed　under　normal　land　based　applications　instead　of　ocean　conditions.　The　modified　correlations　must　be　validated　and　added　into　the　codes　for　ocean　conditions.　Codes　for　ocean　conditions　need　more　systematical　validations.　A　series　of　suggestions　are　provided　for　the　future　work.　©　2016　Association　for　Computing　Machinery　Inc.　All　Rights　Reserved.