Make it so if your underwater riding a boat you run out of oxygen?

So if your boat is flipped upside down make it so you lose oxygen until you exit the seat and swim up to the surface

local bar = script.Parent.BarBG.Bar
local oxygenLabel = script.Parent.BarBG.OxygenAmount

local maxOxygen = 100
local currentOxygen = maxOxygen

local timePerLoss = 0.3
local chairwater = false
local isSwimming = false

local char = game.Players.LocalPlayer.Character
local hum = char:WaitForChild("Humanoid")


hum.StateChanged:Connect(function(oldState, newState)


    if newState == Enum.HumanoidStateType.Swimming then

        isSwimming = true
        script.Parent.Enabled = true

    elseif chairwater == false then
        isSwimming = false
    end
end)
char.Torso.Touched:Connect(function(hit)
    if hit:IsA("Water") and hum.Sit == true then
        chairwater = true
        isSwimming = true
    else
        chairwater = false
    end
end)


while wait(timePerLoss) do


    if isSwimming then

        currentOxygen = math.clamp(currentOxygen - 1, 0, maxOxygen)

    else
        currentOxygen = math.clamp(currentOxygen + 1, 0, maxOxygen)
    end


    if currentOxygen < 1 then

        hum.Health = 0
    end


    local barScale = currentOxygen / maxOxygen
    bar:TweenSize(UDim2.new(barScale, 0, 1, 0), "InOut", "Linear", timePerLoss)

    oxygenLabel.Text = currentOxygen .. " / " .. maxOxygen
    if currentOxygen == maxOxygen then
        script.Parent.Enabled = false
    end
end