Final answer:
The density of seawater is increased by decreasing temperature, increasing salinity, and evaporation, as these processes lead to water molecules being closer together or a higher concentration of salts.
Step-by-step explanation:
The processes that will increase the density of seawater are decreasing the temperature, increasing the salinity, and evaporation.
When the temperature of seawater decreases, the water molecules move closer together, making the water denser. Increasing the salinity adds more dissolved solids to the water, which also increases density.
Evaporation removes water, leaving a higher concentration of salts behind, thus increasing the density of the remaining water. Underwater currents do not inherently increase seawater density; they can redistribute water of different densities but do not change the density of the water itself.