Help! My 1.5 year is still scared of the bath.

My youngest has been scared of the bath since he was tiny he always freaks out. He won't sit in the water and play he just stands and tries to climb out. Well this time he fell and hit his head twice in the same spot and he's got nasty lines on his head from it. How do I get him to chill out in the bath so he doesn't do this again. Will include a picture of his cuts so you can see. I really need to stop it from happening again. Happened last night.