FAQ for
Raiders of the Lost Ark (1981) More at IMDbPro »

The following FAQ entries may contain spoilers. Only the biggest ones (if any) will be covered with spoiler tags. Spoiler tags are used sparingly in order to make the page more readable.

It is the Chachapoyan Fertility Idol, a sacred object that the Hovitos protect.

Assuming the idol is roughly 1/6 of a cubic foot (28 litres), it would weigh approximately 200 lbs (90 kg), assuming that it is actually solid gold. The film, however, never specifies its make-up; it might well have been gold-plated stone or ceramic, seeing as Indy lifts it quite easily.

The most likely explanation for the initially extraordinarily tense relationship with the emotionally turbulent Marion Ravenhood is that Marion had romantic and sexual relations with Indy when she was a young adolescent. The age difference is approximately ten years; Henry "Indiana" Jones would have been in his mid-20s and she around 15 or 16 when they first met and fell in love. The implication is that she felt taken advantage of by the older, more experienced man, an inappropriate relationship which also caused Indy's falling out with her father, Abner.

In Temple of Doom, while interacting with Willie Scott, discussing love-making techniques in humorous context, Indiana Jones mentions "years of field work" in reference to his level of sexual experience.

Yes. Tanis was at one point the northern capitol of Egypt, and in 1939, after extensive excavations, a great deal of treasure and artifacts were found there (however, the Ark was not among them). See here for more details.

There is a deleted scene in which you see Indy holding on to the periscope, which is sticking out of the water.

Also, early submarines generally traveled the oceans on the surface of the water under diesel power, which requires access to the air for inlets to the engines. They could only travel short distances under water, as this required electric propulsion and the battery power of the submarine did not last very long. However, there would generally be four or five crewman on the conning tower as lookouts. U-boats generally would submerge to a depth of roughly 12 meters, deep enough to see out the periscope.

In the novelization, Indy lashed himself to the periscope with his bullwhip and rode/dozed through 20 frigid hours in oceanic water. In the movie, we never see the sub fully submerge, so are left with the conclusion that Indy rode on the top, a more believable senario than riding it underwater without freezing or drowning.

The Ark is put into storage, the government's apparent answer to any problem of this sort. It seems an enormous warehouse has been allocated for the use of placing objects that cannot be used and/or destroyed. The Ark becomes one of many artifacts that are just left with the hope that nobody ever finds them.

The final scene was also meant as an homage to the final scene of Citizen Kane (where Kane's property ended up being stacked into boxes throughout his house).

It is later revealed in the fourth Indy film, Kingdom of the Crystal Skull, that the Ark had been taken to Area 51, a military facility near Groom Lake in Nevada. During the chase scene at the beginning of the movie, you briefly see a broken crate with the Ark partially revealed.