```typescript
export function tideMarks(levels: number[]): number[] {
  if (levels.length < 3) return [];

  const peaks: number[] = [];
  for (let i = 1; i < levels.length - 1; i++) {
    const currentLevel = levels[i];
    const previousLevel = levels[i - 1];
    const nextLevel = levels[i + 1];

    if (currentLevel > previousLevel && currentLevel > nextLevel) {
      peaks.push(i);
    }
  }

  return peaks;
}
```