"Come seek us where our voices sound..."
Yes, that is the opening line of mersong, and rather than search the lake for what we'd miss I've compiled a little section of some of my favorite Viktor and Hermione related quotes from canon. So let's seek Viktor and Hermione where their voices sound:
Goblet of Fire, page 83:
The tents here had not been bedecked with plant life, but each and every one of them had the same poster attached to it, a poster of a very surly face with heavy black eyebrows. The picture was, of course, moving, but all it did was blink and scowl.
"Krum," said Ron quietly.
"What?" said Hermione.
"Krum!" said Ron. "Viktor Krum, the Bulgarian Seeker!"
"He looks really grumpy," said Hermione, looking around at the many Krums blinking and scowling at them.
Goblet of Fire, page 108:
One hundred thousand wizards gasped as the two Seekers, Krum and Lynch, plummeted through the center of the Chasers, so fast that it looked as though they had just jumped from airplanes without parachutes. Harry followed their descent through his Omnioculars, squinting to see where the Snitch was--
"They're going to crash!" screamed Hermione next to Harry.
She was half right--at the very last second, Viktor Krum pulled out of the dive and spiraled off. Lynch, however, hit the ground with a dull thud that could be heard throughout the stadium.
Goblet of Fire, page 114:
"He was very brave, wasn't he?" Hermione said, leaning forward to watch Krum land as a swarm of mediwizards blasted a path through the battling leprechauns and veela to get to him. "He looks a terrible mess...."
Goblet of Fire, page 309:
Viktor Krum got up and slouched, round-shouldered and duck-footed, toward Mr. Olivander. He thrust out his wand and stood scowling, with his hands in the pockets of his robes.
"Hmm," said Mr. Olivander, "this is a Gregorovich creation, unless I'm much mistaken? A fine wand maker, though the styling is never quite what I... however..."
He lifted the wand and examined it minutely, turning it over and over before his eyes.
"Yes hornbeam and dragon heartstring?" he shot at Krum, who nodded. "Rather thicker than one usually sees...quite rigid...ten and a quarter inches... Avis!"
Goblet of Fire, page 317:
Viktor Krum was in the library an awful lot too, and Harry wondered what he was up to. Was he studying, or was he looking for things to help him through the first task? Hermione often complained about Krum being there--not that he ever bothered them--but because groups of giggling girls often turned up to spy on him from behind bookshelves, and Hermione found the noise distracting.
"He's not even good-looking!" she muttered angrily, glaring at Krum's sharp profile. "They only like him because he's famous! They wouldn't look twice at him if he couldn't do that Wonky-Faint thing--"
Goblet of Fire, page 339:
"Oh no, he's back again, why can't he read on his stupid ship?" said Hermione irritably as Viktor Krum slouched in, cast a surly look over at the pair of them, and settled himself in a distant corner with a pile of books. "Come on, Harry, we'll go back to the common room... his fan club'll be here in a moment, twittering away...."
And sure enough, as they left the library, a gang of girls tiptoed past them, one of them wearing a Bulgaria scarf tied around her waist.
Goblet of Fire, page 416:
Harry glanced up at Hermione to see how she felt about this new and more complicated method of dining--surely it meant plenty of extra work for the house-elves?--but for once, Hermione didn't seem to be thinking about S.P.E.W. She was deep in talk with Viktor Krum and hardly seemd to notice what she was eating.
It occured to Harry that he had never actually heard Krum speak before, but he was certainly talking now, and very enthusiastically at that.
"Vell, ve have a castle also, not as big as this, no as comfortable, I am thinking," he was telling Hermione. "Ve have just four floors, and the fires are lit only for magical purposes. But ve have grounds larger even than these--though in vinter we have very little day-light, so ve are not enjoying them. But in summer ve are flying every day, over the lakes and the mountains--"
Goblet of Fire, page 443:
He, Ron, and Hermione left the castle together on Saturday and set off through the cold, wet grounds toward the gates. As they passed the Durmstrang ship moored in the lake, they saw Viktor Krum emerge onto the deck, dressed in nothing but swimming trunks. He was very skinny indeed, but apparently a lot tougher than he looked, because he climbed up onto the side of the ship, stretched out his arms, and dived, right into the lake.
"He's mad!" said Harry, staring at Krum's dark head as it bobbed out into the middle of the lake. "It must be freezing, it's January!"
"It's a lot colder where he comes from," said Hermione. "I suppose it feels quite warm to him."
"Yeah, but there's still the giant squid," said Ron. He didn't sound anxious--if anything, he sounded hopeful. Hermione noticed his tone of voice and frowned.
"He's really nice, you know," she said. "He's not at all like you'd think, coming from Durmstrang. He likes it much better here, he told me."