The opposite of an ebb tide is a flood tide, according to The Fishing Line. The flood tide is the incoming water as the tide changes from low to high, and the ebb tide is the outgoing water as the tide goes from high to low.
The tide changes throughout the day, with two high tides and two low tides occurring daily. The sea level rises over several hours as the flood tide comes in until the water reaches high tide. Then, the sea level falls over several hours as the water recedes during ebb tide until the water reaches low tide.