I'm sure a few of these have been touched on but
- Ways to collect fish in bulk (like a net) and introduce other types of sea food- clam, squid, seaweed
- Ability to dive and collect/explore
- Use ability to collect plastic litter and craft into items (like snorkel gear)
- Different player modes like seen in Minecraft: Survival (Easy, Medium, Hard), Casual (no shark but still thirst and hunger), Exploration (crafting but immortal), Free build (all resources and unlimited health)
-Introduce other threats like weather
-a bed (or hammock) to get through the night or recouperate health
-I saw the mention of islands and boats and really like the idea