In a word, Yes. The Pacific Ocean and the Atlantic Ocean mix. However, it is not as simple as two bodies of water simply blending together.
Do the Pacific Ocean and the Atlantic Ocean mix?
Fact check: Atlantic, Pacific oceans mix regardless of clay and iron
Where the Atlantic ocean and the Pacific ocean meet, what prevents salt water from mixing with fresh? - Quora
Why the Atlantic and Pacific Oceans Don't mix Atlantic and pacific oceans don't mix #Oceans
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Ocean Geography ~ MarineBio Conservation Society
Ocean Circulation & Stratification - Time Scavengers
Undersea mountains stir up currents critical to Earth's climate, Science