So, you dropped your phone and it fell into the water? Here's what you should do.
1- Quickly take the phone out of the water.
2- Do not try to turn the phone on, do not try to charge it, do not shake the phone, do not press the buttons (it could force the water further into the circuit board) and most importantly, do not use a blow dryer to dry the phone as it might worsen the damage to your phone.
3- Remove anything that is removable such as the battery (if it's not built in), your memory card, the SPEN, and the SIM card.
4- Use a towel to gently dry the phone.
5- Let your phone to dry for at least 24 hours minimum, be creative to put in the rice container (us Asians sure have heard of this) or with silica gel pack or a phone drying pouch.
6- After some day(s), you can try to insert the battery and try switching it on.
7- If it doesn't turn on, try charging it.
8- If it doesn't work by applying above methods, it is time to visit a Samsung Authorised Service Centre and let the pros have a look at it.
Note: IP68 means it is highly resistant to dust, dirt, sand, and water damage (based on test conditions for submersion in up to 1.5 meters of freshwater for up to 30 minutes.), but it doesn't mean the phone is waterproof.
