The Glowing Sea

The Glowing Sea is a main story quest in Fallout 4.

Detailed walkthrough
Kellogg's memories and Doctor Amari's advice indicate that the Sole Survivor should locate an escaped Institute scientist, Virgil. His last known position was deep in the most irradiated region of the Commonwealth, the Glowing Sea.

Before embarking on this quest, consider how one will deal with high radiation levels for an extended period of time. A hazmat suit, or power armor will suffice, along with a supply of RadAway. Head southwest, following the remains of the freeway until the Pip-Boy indicates a hike off-road is in order. One can expect to face deathclaws, radscorpions, feral ghouls and other irradiated wildlife. When reaching the map marker, the Survivor will find themselves close to the Crater of Atom, a site holy to followers of the Church of the Children of Atom.

When entering the location of a strange cult, led by Mother Isolde, one is in fact, trespassing. Though violence is always an option (search the area for a scrap of paper indicating a nearby cave), it is possible to lower one's weapon and speak to Mother Isolde instead. Answer her politely and she will direct the player character to a rocky cave nearby.

Locate the rocky cave roughly southwest of the Crater of Atom, being wary of the roaming deathclaw in the area. Virgil will be found inside this cave. He requests that the Survivor help him locate a serum within the Institute, in return for his knowledge.

Bugs
Upon entering the cave, Virgil is not there. The marker for finding him points to the ground. This may be the result of having visited Virgil's cave prior to the quest.
 * On PC, using console command and then  may force Virgil to appear in the cave.

Das Leuchtende Meer Mar Resplandeciente (Misión) O Mar Reluzente Светящееся море (квест) Море, яке світиться (квест)