The Saltwater Room

My personal interpretation (really long)

"I opened my eyes last night and saw you in the low light"

lowlight: a particularly bad or unpleasant event, detail, or part

he saw her in an unpleasant way he did not want to see her in. He discovered a part of her personality that he missed before... this time he saw her in a negative or sad light for the first time.

"Walking down by the bay, on the shore, staring up at the planes that aren�t there anymore"

In every single song, Owl City mentions some mode of transportation as some sort of metaphor. In this case, the planes represent bygone memories that the boy& girl are reminiscing together, late into the night. 

"I was feeling the night grow old and you were looking so cold Like an introvert, I drew my over shirt Around my arms and began to shiver violently before"

The lyrics here suggest that both people want more warmth/heat between their interactions, despite their history. 

"You happened to look and see the tunnels all around me Running into the dark underground All the subways around create a great sound To my motion fatigue: farewell"

The singer always links himself to modes of transportation so the tunnels around him are probably the relationship choices the girl can make that involves him. However, all solutions to work towards a relationship seems grim ("running into the dark underground"). The guy is getting tired of the limbo situation he has with the girl... dating, not dating, dating not dating, fighting, making up, etc ("to my motion fatigue: goodbye"). He either wants to take initiative and make this relationship finally work or give up.

"With your ear to a seashell You can hear the waves in underwater caves As if you actually were inside a saltwater room"

With their imagination, the the relationship would be idealistic. However, Owl City reinforces that this idealized picture of relationship is different from reality ("As if..."). When you press your ears against a seashell, you can pretend you're by the ocean and underwater paradise. Perhaps here the singer is talking about a long distance relationship; when you talk to a person online or on the phone, you can pretend you are also somewhere else... with significant other. 

"Time together is just never quite enough When you and I are alone, I�ve never felt so at home What will it take to make or break this hint of love?"

They keep telling themselves that with more time, they will eventually make everything work. However, due to long distance, they never get to spend enough time together to make the relationship concrete and stable. However when they are together, they've very comfortable with each other. THis is why they think extra efforts in making the relationship work is worth it. However they're tired of staying in the gray area.

"We need time, only time When we�re apart whatever are you thinking of? If this is what I call home, why does it feel so alone? So tell me darling, do you wish we�d fall in love? All the time, all the time"

Whenever they're apart, they feel a bit lonely when they carry on their daily activities. They wish there could be a fair chance at love. No distance, no time constraints, no past history.

"Can you believe that the crew has gone and wouldn�t let me sign on? All my islands have sunk in the deep, so I can hardly relax or even oversleep"

The guy feels lost. He feels like he's losing his mind/sleep over this relationship (or lack thereof).

"I feel as if I were home some nights when we count all the ship lights"

The ship lights (note another mentioning of transportation) might represent hopes of the girl/boy being together... or perhaps the counting of the lights just signifies that the time they spend together feels so natural.

"I guess Ill never know why sparrows love the snow Well turn off all of the lights and set this ballroom aglow"

The guy thinks that they'll never know what will happen if the relationship is given another chance (with no distance, etc), but he decides to enjoy the present, in the presence of the girl.