We study how ocean currents and tides affect melting near the base of a glacier like the Thwaites Glacier, a major source of sea-level rise in West Antarctica. Using a high-resolution ocean model, we show that even weak coastal currents can trap cold water near the glacier by pushing down lighter meltwater, forming a stable freshwater layer. Changing current direction or adding freshwater from beneath the glacier can disrupt this balance. Tides create multiple layers of meltwater and mix heat toward the ice. Our results show that realistic ocean dynamics are essential for understanding how quickly the glacier may retreat in the future.