Walkthrough: After saving Nebby and helping out Lillie, a player can either follow her or check out Seaward Cave that has an entrance in Melemele Meadow. Seaward Cave is full of Wild Pokemon, and it leads to Kala'e Bay.
Wild Pokemon:
Standard Walking (Levels 9-12): Zubat(70%), Diglett(30%)
Surfing (Levels 15-18): Zubat(80%), Psyduck(20%)
Fishing (Levels 10-15): Magikarp(99%), Barboach(1%)
Fishing SOS Pokemon #1 (Levels 10-15): Gyarados, Whiscash
Fishing SOS Pokemon #2 (Levels 10-15): Magikarp, Barboach
Fishing Bubble Spots (Levels 10-15): Barboach(50%), Magikarp(50%)
Fishing Bubble Spots SOS Pokemon #1 (Levels 10-15): Whiscash, Gyarados
Zygarde Cells: There are no Zygarde Cells found in Seaward Cave.
Trainers: There are no trainers within the cave either.
Items:
Escape Rope - Near East Exit
Heal Ball - Near Rock on Path
Max Revive - Across North Water
Super Potion - On Bottom Part of Cave
Never-Melt Ice - On Ledge Near East Exit
Expert Belt - Near Tauros Rocks
Star Piece - In Rock On Southern Part of Cave (Hidden)
Stardust - In Rock By Lowest Exit (Hidden)