First, the good:
- It offers a way to use stamina aside from crafting.
- It gives more value to the Stamina talent.
- It encourages more people to participate in the fishing contests.
- It has completely devalued most 7* weapons in the game.
- The scope of rewards seems to be small.
- It is not engaging in any way; just click a lot.
Regarding the first and second "bad" aspects to diving, my recommendation is to expand the items which can be found in chests. I think the spawn rate for chests is fine, but from my experience you're almost guaranteed to get a 7* weapon or accessory when you open it. Expand the rarity range for weapons and accessories found in chests, maybe from 3* all the way up to 10*, with drop rate decreasing as rarity increases. And to be clear, I'm talking about maybe a 1/1000 chance of getting a 10* item. The point of this suggestion is not to snag more rare items for myself; rather, it is to return value to 7* items by making them appropriately rare, and to be a carrot on a stick for those who are currently uninterested in diving.
"Why would I use the new diving feature? I don't want any stupid katanas."
"Wow, you can get 9* and 10* items from diving now? I'm gonna do that every time my stamina regenerates!"
Now the issue of it not being engaging. There's really not much I can think of here aside from maybe the addition of different types of chests. For example, maybe a special kind of chest can spawn which must have its lock picked to open, similar to chests in the overworld. And for those who do not take the lockpicking talent, maybe an additional type of rusty chest may spawn that cannot be opened, but must be smashed; players with decent STR can do this. These special chests could contain items just like the normal chests, but also a small amount of murai and/or sea tokens.
Maybe add some additional random rewards from kelp based on your level of the Gatherer talent, and additional rewards from bones based on your level of the Miner talent. Could even do the same for coral based on the Scavenger talent? Not really sure, and this particular portion of the suggestion is not hugely important. Might just be worth considering.
And one very last quick note on the sea token shop. For the most part, I think it has some pretty good items on offer - particularly the enchants, the diving helmet and the treasure map. But here are a few ideas for other items you could add.
- An anchor (accessory) which grants immunity to knockback, similar to Spiked Treads.
- A seaman's telescope (accessory), which reveals statistics similar to Setsuna.
- A bottle of ancient rum (accessory) which increases evasion but induces poison.
I'm sure the community can think of many more of these, but the effects of the current weapons are... only decent, and very situational.