These three adventures are suitable for the Pirate Khanate of Astrakhan, as detailed on the wiki. Presume the details of one adventure has no definite application to the details of any other.
Frozen in Ice
The party arrives in winter (by land or by sea) to find a merchant ship some forty miles from the city of Astrakhan, in the great swampy delta of the Volga river - trapped by the frozen mud of the swamp. Most of the easy-to-carry contents of the vessel have been moved to another location, but upon investigation (and having to clear out a few pests and vermin that have used the ship as a home for the winter to protect them against the wind) the party will find that the value thousands of gold pieces remains in the hold, in the form of several great bales of wool (500 lbs. apiece), a thousand sacks of rice and a thousand sacks of wheat, barrels, massive pieces of furniture or whatever else amounts to make it enough to get the party interested. In all, however, it is far too heavy to haul enough of it across the treacherous ice to account for the value of everything.
Additionally, by the time the players clear out the beasties, the day turns warm and the vessel shifts. Upon investigation, the ice in the channel is not as deep as first supposed; this vessel may be clear of ice within two weeks. From all appearance, it seems sturdy and seaworthy.
However, it is also apparently an owned vessel . . . and surely its owners are well aware that the ice is melting. When will the owners return? How many of them will there be? Is it possible the party could fight them off and take possession of the ship? How wrong could that be, since the whole territory is controlled by pirates!
While in Astrakhan in late spring to summer, the party is warned that a swarm of locusts has been sighted fifty miles east of the city. This swarm is moving westward at a speed of twenty-five to fifty miles a day - and according to reports from druids, the swarm is easily 80 miles in diameter. There is much talk of the swarm missing Astrakhan as it did three years ago; or possibly hitting Astrakhan directly as it did ten years ago.
Presuming the party doesn't have the means to outrun the swarm, and they realize it, they will be in Astrakhan when the swarm hits 18 hours later. The locusts are two inches in length but do not have a sufficient mass to have a single hit point; however, as a swarm they will cause 2 damage per round to anyone caught outside. The party will hear the swarm before it arrives. The locusts will be magically augmented - so as a group they will eat any flesh, fresh wood, any wood that has been greased, even thatch on roofs. If the party has horses, they will hear the horses crying out when the stable proves to be less than airtight; the party will have to move the horses into one of the brick/mud buildings to save them. The upper floor of the inn where they're staying will be eaten away and exposed, forcing the party to somehow seal up the stone stairwell or move to the cellar for the duration. A number of tropes can be stolen from zombie films to round out the adventure.
If the party tries to flee in any direction before the locusts arrive, without travelling at least 50 miles within 18 hours, presume they will be caught in the swarm. Put a building they can reach, but place it so that the number of rounds the players must endure the insect swarm attack is 5-20. Make the building interesting, have the players force their way into a family, force them to spend an hour killing locusts, give a chance for disease, etc.
If the party can easily manage this adventure, don't run it.
Opportunities for Profit
The party hears about a pirate raid on an orcish fleet bringing goods from Gilan (a Safavid province in Persia) on the south coast of the Caspian to trade with orcs from Digoria (another orc land) on the west at the mouth of the Kuma river, which is thinly guarded/inhabited. 18 galleys were caught in shallow water by Astrakhan Pirates and run aground, the galleys sunk in five to eight feet of water.
Unfortunately, though the pirates were successful, there were far too many goods for them to take back to Astrakhan. Bales of tea and cotton have been taken to the station at Langan and dumped, where they are guarded by only fifty or sixty humans; word is that there are boxes of pistachios, almonds and tobacco strung out along miles of beach south of Langan. Supposedly, the pirates found a treasure in raw silk cloth and silken goods that they took to Astrakhan, but others say they didn't get all of it.
If the party is in Astrakhan, they may choose to join an exodus of a thousand who rush out of the city as though this were a gold rush (learning that this sort of thing happens once or twice a season). If the party is in Kalmykstan, west of Langan, they will hear about the booty AND the rush of people from Astrakhan.
They can, if they wish, try to find undefended goods on the beach, where they might have to fight other parties doing the same thing (not to mention orcs along the Kuma seeking to gain what was promised to them). There might even be Safavids by land or by boat taking part. If this is the party's plan, make it a great free for all.
Otherwise, the party might try to seize goods from Langan or BUY them (as they could then sell them for a good price elsewhere) at 25% of cost in Astrakhan. Of course, if the party does this, they will then have to defend the goods if any other large groups come to seize them before the Astrakhan pirates get back to get the rest of what they've left behind. The DM shouldn't assume they don't.