Replacing dimmer switch that controls pool and spa lights

We have 2 different dimmer switches installed outside that control the pool and hot tub.  We want to replace them with normal “on/off” switch.  They don’t work well and you never know when the lights are truly on or off.  Does anyone have skill in this area?  Is it hard to replace?  I would think it’s fairly simple but since the switches are outside on a pole I wasn’t sure if there is a special type of switch for outside.  Thanks