In　this　article,　a　novel　localization　approach　incorporating　attitude　and　heading　reference　system　and　underwater　altimeters　is　presented　to　accurately　localize　the　underwater　welding　vehicles　in　spent　fuel　pools　of　the　nuclear　power　stations.　Different　from　the　conventional　underwater　localization　technologies,　the　presented　localization　approach　is　a　more　suitable　approach　in　cases　of　confined　structured　water　areas.　Firstly,　a　multi-regions　division　localization　algorithm　is　proposed　for　calculating　the　coordinate　of　the　underwater　welding　vehicle　through　data　from　sensors.　Also,　considering　the　attitude　errors　of　the　underwater　welding　vehicle,　the　beam　angle　of　the　altimeters,　and　the　boundary　effects　of　cross-regions,　an　optimized　multi-regions　division　localization　algorithm　is　introduced　for　general　applicability　of　the　multi-regions　division　localization.　Then,　computer　simulations　are　employed　to　evaluate　the　validity　and　the　performance　of　multi-regions　division　localization　and　optimized　multi-regions　division　localization.　Finally,　the　efficiency　of　the　proposed　approach　is　confirmed　via　system　experiments.　The　experimental　results　are　consistent　with　simulation　results　which　further　indicate　that　the　presented　approach　holds　great　potential　in　effective　underwater　vehicles　localization　for　confined　structured　water　scenarios.　©　The　Author(s)　2019.