There is news from India today on continued archaeological efforts to identify the site of the ancient Indian city of Muziris, one of the most important ports for trade between India and Rome.
Traders from Alexandria and the rest of Roman Egypt would wait until July to set out for India. Under typical conditions, it was a two month journey, but departing any sooner would place a ship off India's southwest coast during the most dangerous sailing conditions of the year—even modern maritime insurers are reluctant to offer summer coverage in the area.
For the wealthy, high-powered Alexandrian merchants who could afford to underwrite such expensive voyages, the payoff was enormous. Arriving in India in September and leaving in December, the traders would ride home on the winds of the northeast monsoon, hulls packed with incense, myrrh, ivory, spices, silk, wild animals, pearls, and other luxuries of the Far East. After they docked at the Red Sea ports of Berenice or Myos Hormos, caravans would take the goods across the eastern desert to Alexandria, where other ships would distribute them—with a very profitable markup—across the Mediterranean heart of the empire.
Roman exports to India were paltry by comparison, and at least one contemporary felt that Rome was getting a raw deal. Pliny the Elder, writing in the first century AD, lamented that "in no year does India drain our empire of less than five hundred and fifty millions (!) of sesterces, giving back her own wares in exchange, which are sold among us at fully one hundred times their prime cost." (Natural History 6.26)
ETA: Adrian Murdoch, who graciously sent some readers my way on Friday, thinks about this stuff for a living. I'm not surprised to discover that he posted on this dig when the first news releases hit the wire last summer.