local int tunnelLength = 20

local function tunnel(int)
	for i = 0, int do
		turtle.dig()
		turtle.forward()
	end
	turtle.turnLeft()
	turtle.turnLeft()
	for i = 0, int do
		turtle.forward()
	end

turtle.turnLeft()
tunnel(tunnelLength)
tunnel(tunnelLength)
turtle.turnRight()