When He got into the boat, His disciples followed Him.
As we shall soon meet again with the mention of a lake, where it is said (Matthew 8:33) that the swine were carried into it with violence, it is not universally agreed whether one and the same lake is mentioned in both places.
Christ chose the sea deliberately to reveal Himself as God over all creation. Those who truly follow Him must be willing to go with Him into peril and difficulty, not merely walk the safe land-way; discipleship means venturing wherever He leads, ship or prison alike.
AI summary
Commenting on Matthew 8:23-27
And behold, there arose a great tempest,.... "A great concussion", or "shaking" of the sea; the stormy wind moved the sea, and the waves thereof; and both wind and sea shook the ship, and the men that were in it.