Only the peisteskin maps are required to have a FULL PARTY of 8 to open the coffer.
You can not start the fight with anything less than 8.
That in mind.. Chocobo's count as members so a min. of 4 actual players are required.

Any other map : leather , toad and boarskin are all solo maps. you can decipher and dig these by yourself.

So back to the peisteskin map: So the lot of you that comment on this thread... would agree.. you join the hunt offer nothing in return other than your time and deserve to get the /rare loot? I understand that gil and other items get split among everybody.

but the /rare loot > Blue Bird minion that sells for 500,000 should be just randomly given away ? I took the time to level a Gathering class to 50 and then farmed away at level 50 nodes for sometimes 30 min or longer to get the peisteskin map to pop. Yet it's ok to lose this /rare drop to someone because they are a place holder ? Whatever..