After leaving the island of women and sex, the Argonauts travel through a straight called Hellespontos, searched the islands found there. They make friends with a king named Cyzicus of the island Propontis. Cyzicus was a friendly newly wed and close to Jason in age, so the two hit it off immediately. Cyzicus suggested that the Argonauts search an area beyond Bear Mountain for the Golden Fleece, but the fact that the region was inhabited by six-armed giants somehow slipped his mind. The giants raided the ship. Hercules and a few others managed to fend them off, but many of the supplies were ransacked.
The Argonauts needed more supplies, so they set about searching the forests for food, water, and wood for repairs. Hercules sent his current romantic interest or son depending on what source you’re reading, a young man named Hylas, to get water. Hylas somehow managed to get himself drowned by water nymphs or kidnapped and married to a water nymph, but his body wasn’t found, so Hercules ended up staying behind to search for Hylas while the Argonauts continued their quest. The timing of this bit varies. I think it makes the most sense here, but many sources list this happening after the events of the next paragraph.
The Argonauts headed back to King Cyzicus, but got lost along the way. They arrived near Cyzicus’ home when it was dark, and Cyzicus’ people, the Doliones, mistook the Argonauts for enemies and attacked. A bloody battle ensued, many died, including Cyzicus. Both sides realized their mistake when the sun rose, and an epic funeral was held and Cyzicus’ wife committed suicide. Bad weather keeps the Argonauts on the Propontis shore for several days until a local seer starts a new cult to appease the gods.
Some of the Argonauts are unhappy with Jason’s decision to leave Hercules behind. Or rather Jason’s decision to respect Hercules’ request to stay behind. Mutiny looked likely, but in classic Deus Ex Machine, Glaucus, a random sea god and prophet pops up to reassure the crew that Herc leaving was meant to be.
Let’s talk about Glaucus for a minute. Glaucus was born a mortal fisherman. He discovered a special herb that brought the fish he caught back to life and decided to try it for himself. The herb made him immortal and a prophet, but it also turned him into a fishman. Think of the least attractive variation of merman you can imagine and you’re close. Oh, and he may have been immortal, but he still aged. Some sources say he built the Argo, though Argus is typically credited with building the ship. Glaucus watched over sailors and such. He stuck around the Argo as well, helping it out of storms and unmoving seas and chatting with the crew and throwing random prophesies at them. Glaucus was probably kind of bored. He used to be human, so human interaction was a must. It also helped that he was a huge fan of Orpheus.
Glaucus fell in love with the sea nymph Scylla, but she was turned off by his fish man vibe, so she rebuffed his affections. Desperate and devastated, Glaucus begged Circe for a potion that would make Scylla love him. Circe fell in love with him instead, and begged him to choose her. Glaucus refused saying he would never stop loving Scylla, so Circe turned Scylla into a monster. He later moved on to seduce Ariadne, the maze-solver, but lost her to Dionysus later. Glaucus went on to love many other men and women, depending on the myth.
Anyhow, appeased that the missing crew members (Hylas, Herc, and Polyphemus (he stayed with Herc to search) were part of a divine plan, the crew go on their merry way and continue the quest for the Golden Fleece.