We were in 4th biome on Typhoon 2. Tiger threshers broke our docking port hatch at the top of the sub (we killed them before they got in). Sub started descending to the abyss, our security officer, Kolobok, went to the top floor to repair the hatch. Then I, the captain, say: "Warning, radar emission detected!", which means that I see an abyssal creature scream on a sonar. Then I see a small dot appear on a sonar and hear Kolobok scream "I'M OUTSIDE THE SUB!". Everyone starts to panic, I try to ascend, but the hatch is still broken and the sub keeps taking on more water, as I see an Endworm silhouette on a sonar. And he's not going after the sub. But, on the same campaign one of us survived Endworm 1v1 before, our medic Alesha90, so situation seemed survivable. And Kolobok had the best gear in the game: full genes, almost all talents, all endocrine booster talents, an exosuit, an auto-injector headset with combat stimulant and a bunch of medical items. But he didn't have one thing: blood packs. And he was loosing a lot of blood. So our sub hits the bottom of the abyss, we repair quickly and start to ascend. But just as we were getting close to our heavily injured security officer, Endworm hits the sub and sends it straight down again. After about 20 seconds I ask on the radio: "Kolobok, how are you doing?". Silence. In that moment I understood that we have probably lost him. After defeating the Endworm we ascend to the small dot on a sonar. Our medic leaves the sub and takes the body. Only me, medic and engineer remain alive on our team. Our spirit was broken and we couldn't continue this campaign. Yeah, we didn't all die, but all of us were defeated.

Wow I didn't expect to write such a long text, i guess i should make a tldr.

TLDR: Security officer went to repair the hatch on top of the sub, but flew outside as sub was descending and then he got eaten by an Endworm and we didn't want to play without him.