The week 10 epic quest requires you to eliminate a player while swimming.

The island is surrounded by water and there are many rivers flowing throughout. This quest will likely attract many players to the water so it shouldn't be hard to find a player near water.

If the battle bus passes over Sweaty Sands make sure you jump as it will likely be a hot drop so many players will be around to eliminate. There is also plenty of loot so you can get ready then go for a swim.

If you can't find any players near water you can shoot your gun to make some noise and hopefully it will draw some players to your position.