In Luke, by which lake was Jesus standing when he taught from Simon's boat?

Answer: Lake of Gennesaret

Luke calls it the Lake of Gennesaret, another name for the Sea of Galilee. Jesus taught the crowd from Simon's boat.

“On one occasion, while Jesus was standing by the Lake of Gennesaret with the crowd pressing in on Him to hear the word of God,”— Luke 5:1 (BSB)