Answer:
Salt water is more dense than freshwater.
Explanation:
A boat is always able to float on water because it experiences an upthrust upwards.
The magnitude of the upthrust depends upon the density of the liquid.
When the liquid is denser the boat will experience a high upthrust as compared to when in a less dense liquid.
Now, ocean water consists of salt which makes it more dense, thus If the boat sinks lower into the water in a freshwater lake than in ocean, then Salt water is more dense than freshwater.