Why does my script see players as always swimming?

This is the log over 8.5 seconds: 21:32:32.155 - Baseplate was auto-saved (x2) swimming (x17)

local p = game.Players.LocalPlayer
local c = p.Character
local m = p:GetMouse()

local sprint = false

local t,f = true,false

local w,a,s,d = f,f,f,f
local wt = 0

function lower() -- player starts drowning if they are swimming
	c.Humanoid.Health = c.Humanoid.Health -1
end


m.KeyDown:connect(function(key)
	if key == '0' then
		sprint = t
	end
	if key == 'w' then
		w = t
	end
	if key == 'a' then
		a = t
	end
	if key == 's' then
		s = t
	end
	if key == 'd' then
		d = t
	end
end)
m.KeyUp:connect(function(key)
	if key == '0' then
		sprint = f
	end
	if key == 'w' then
		w = f
	end
	if key == 'a' then
		a = f
	end
	if key == 's' then
		s = f
	end
	if key == 'd' then
		d = f
	end
end)

while wait() do
	wt = wt - .01
	if wt <= 0 then
		if script.Parent.Frame.Bar.Size.X.Scale < .9 then
			script.Parent.Frame.Bar.Size = script.Parent.Frame.Bar.Size + UDim2.new(.009,0,0,0)
		end
	end
	if w or a or s or d then
		if script.Parent.Frame.Bar.Size.X.Scale > 0 and sprint then
			script.Parent.Frame.Bar.Size = script.Parent.Frame.Bar.Size - UDim2.new(.009,0,0,0)
			c.Humanoid.WalkSpeed = 20
		end
	end
	if sprint then
		wt = 1.3
	end
	if not w and not a and not s and not d then c.Humanoid.WalkSpeed = 12 end
	if not sprint then c.Humanoid.WalkSpeed = 12 end
	if script.Parent.Frame.Bar.Size.X.Scale <= 0 then c.Humanoid.WalkSpeed = 12 end
	if c.Humanoid.Swimming:connect(lower) then print("swimming") wait(0.5)end -- detects if a player is swimming
	end

Swimming is an event of the Humanoid object.. you can't "check" an RbxScriptSignal and expect it to return if the player is swimming or not.

I suggest you use the StateChanged event of the Humanoid object. It fires when the state of the humanoid changes(e.g. Jumping, Falling, Dead, swimming). It returns the previous state of the humanoid, and the current state.

You can compare the second returned value with the HumanoidStateType Enum.

local p = game.Players.LocalPlayer
local c = p.Character or p.CharacterAdded:Wait()
local h = c:WaitForChild("Humanoid")
local target_state = Enum.HumanoidStateType.Swimming
local swimming = false

h.StateChanged:Connect(function(old,new)
	if new == target_state then --Compare current state
		swimming = true
		print(c.Name.." went from "..tostring(old).." to "..tostring(new).."!")
	else
		swimming = false
	end
end)