When evening came, he was there alone, but the boat was already a considerable distance from land, buffeted by the waves because the wind was against it. During the fourth watch of the night Jesus went out to them, walking on the lake. When the disciples saw him walking on the lake, they were terrified. Immediately Jesus reached out his hand and caught him. And when they climbed into the boat, the wind died down.
Some people think there's something wrong with walking on water.
Hey, there's nothing wrong with walking on water. Not as long as your Lord has bidden you to do exactly that. But there is something wrong with doubting while you're doing it. The text says so. It says, when the wind terrified him and he doubted, Peter began to sink.