First you start above the water 
You have to overcome simple obstacles or fall into the water 

Then it gets a little bit harder. 
You have to skip this place and the problem is that its ceiling is short so watch out

Then you have to skip this parkour , you have to not fall into the magma block 

and then reach the interesting place you have to skip this place first by pressing ctrl in order to skip the place and reach the next one by passing from 1 block 

Then you overcome this obstacle but first you have to drink potion 
Then you stay in the line and stay away from the magma block

Then you stay in the line and stay away from the magma block and then you reach Parkour, some of it is difficult and some of it is easy until you reach the water temple and win