) ▁around ▁the ▁open ▁Atlantic ▁ocean ▁( including ▁the ▁South west ▁Atlantic ) ▁and ▁in ▁the ▁Indian ▁Ocean . ▁Nevertheless , ▁the ▁Portuguese ▁had ▁to ▁h ire ▁local ▁pil ots ▁in ▁the ▁Indian ▁Ocean ▁for ▁several ▁dec ades ▁to ▁guide ▁their ▁ships . ▁ ▁In ▁the ▁ 1 5 th ▁and ▁ 1 6 th ▁centuries , ▁the ▁Crown ▁of ▁Cast ile ▁and ▁then ▁the ▁" un ified " ▁Crown ▁of ▁Spain ▁was ▁also ▁in ▁the ▁v angu ard ▁of ▁European ▁global ▁expl oration ▁and ▁colonial ▁expansion . ▁The ▁Spanish ▁Crown ▁opened ▁trade ▁routes ▁across ▁the ▁o ce ans , ▁spe cially ▁the ▁trans at l antic ▁exped itions ▁of ▁Christopher ▁Columb us ▁on ▁beh alf ▁of ▁Cast ile , ▁from ▁ 1 4 9 2 . ▁The ▁Crown ▁of ▁Cast ile , ▁under ▁Charles ▁I ▁of ▁Spain , ▁also ▁spons ored ▁the ▁first ▁expedition ▁of ▁world ▁circ umn avigation ▁in ▁ 1 5 2 1 . ▁The ▁enter prise ▁was ▁led ▁by ▁Portuguese ▁navig ator ▁Ferdinand ▁Mag ellan ▁and ▁completed ▁by ▁the ▁Spanish ▁Bas que ▁Juan ▁Sebast i án ▁El cano . ▁The ▁tri ps ▁of ▁expl oration ▁led ▁to ▁trade ▁fl our ishing ▁across ▁the ▁Atlantic ▁Ocean ▁between ▁Spain ▁and ▁America ▁and ▁across ▁the ▁Pacific ▁Ocean ▁between ▁Asia - P ac ific ▁and ▁Mexico ▁via ▁the ▁Philippines . ▁Later , ▁And rés ▁de ▁U rd an eta ▁discovered ▁the ▁northern ▁Pacific ' s ▁volta ▁do ▁mar ▁return ▁voyage . ▁ ▁The ▁comp ass , ▁a ▁cross - st aff ▁or ▁ast