While there have been a smattering of moments here and there, in episode 5, Haruka and Rin show concern over Makoto's fear of the ocean.
Also from episode 5, after talking with Gou, Rin, in his first moment of brotherly love for her, offers to walk her back to the lodge she's staying at. The look on Gou's face says it all - she's so happy that her big brother wants to spend some more time with her.
Many moments in episode 6. We again have Haru showing a lot of concern for Makoto, Makoto - as always - trying to put his friends at ease and not blaming Rei for what happened, Nagisa doing his best to cheer up the others...
Nagisa: If you're scared of the ocean, why did you participate in this training camp?
Makoto: Because I wanted to swim... because, I wanted to swim with you guys.
Makoto: When the four of us swim together... I feel like we can go anywhere.
Rin going running the morning after the storm and deliberately going by the Iwatobi team's tents to make sure they're okay.
When Haruka comes home late after everyone fails their qualifying rounds in episode 8...only to find Makoto asleep on his doorstep, holding his phone. He picks up the phone and hears a message from Nagisa, Rei and Gou, all begging him to come home and swim a relay tomorrow. Haruka wakes Makoto up - and agrees to swim the relay.
Rin still remembering the strokes that are so characteristic for his friends. Him apparently realizing WHAT it was that he taught Haru what else could be important to swimming victories aside. Him getting positively jealous of Rei... ... pretty much all of the scene is both heartwarming and a Moment Of Awesome. ... just like pretty much all of the episode.
The promo art and assorted posters and CD covers tend to have their share of sweet moments.
The cover for volume 2 of the drama CD◊. Kou being happy to spend time with her brother, Rei and Nagisa walking together in the back and for once not getting on each other's nerves, and in the fore we have Makoto sharing something on his phone with Haruka who is smiling.
In episode 9, Haru buys goldfish for Makoto at the festival.
Episode nine itself was practically a crowning episode of heartwarming, with Haru actually smiling and realising how much he loves swimming with the rest of the group. Their faces when he tells them this are priceless. The Power of Friendship at its finest.
The fact that he's crying as he's smiling and saying that he wants to swim with them again. The boy finally showed some emotion towards his friends instead of having Makoto translate.
Episode 11 really shows how much Haruka's opened up, and it's incredibly sweet every time. The once-stoic-faced boy smiles many times in this episode, in response to his teammates and friends, and he has a few sincere heart-to-hearts with each of them. His Brutal Honesty seems to have developed into a knack for being direct but saying exactly what people need to hear.
Also in Episode 11, Haru thanking both Makoto and Nagisa for their friendship. Their reactions of pure elation are something to be seen.
Episode 12 in its entirety. Rei letting Rin take the Butterfly leg of the relay. Rin crying and hugging Haruka and apologizing. Everyone hugging Rin. The picture at the end with the Iwatobi Swim Club (including Rei) plus Rin, who is beaming. Just. Rin smiling. Rin being happy. Everyone being happy. Feelings abound.